diff --git a/codex-rs/Cargo.lock b/codex-rs/Cargo.lock
index aa22911b..15a62983 100644
--- a/codex-rs/Cargo.lock
+++ b/codex-rs/Cargo.lock
@@ -531,6 +531,7 @@ dependencies = [
  "patch",
  "path-absolutize",
  "predicates",
+ "pretty_assertions",
  "rand",
  "reqwest",
  "seccompiler",
diff --git a/codex-rs/README.md b/codex-rs/README.md
index 827a5659..fa724420 100644
--- a/codex-rs/README.md
+++ b/codex-rs/README.md
@@ -109,6 +109,52 @@ approval_policy = "on-failure"
 approval_policy = "never"
 ```
 
+### profiles
+
+A _profile_ is a collection of configuration values that can be set together. Multiple profiles can be defined in `config.toml` and you can specify the one you
+want to use at runtime via the `--profile` flag.
+
+Here is an example of a `config.toml` that defines multiple profiles:
+
+```toml
+model = "o3"
+approval_policy = "unless-allow-listed"
+sandbox_permissions = ["disk-full-read-access"]
+disable_response_storage = false
+
+# Setting `profile` is equivalent to specifying `--profile o3` on the command
+# line, though the `--profile` flag can still be used to override this value.
+profile = "o3"
+
+[model_providers.openai-chat-completions]
+name = "OpenAI using Chat Completions"
+base_url = "https://api.openai.com/v1"
+env_key = "OPENAI_API_KEY"
+wire_api = "chat"
+
+[profiles.o3]
+model = "o3"
+model_provider = "openai"
+approval_policy = "never"
+
+[profiles.gpt3]
+model = "gpt-3.5-turbo"
+model_provider = "openai-chat-completions"
+
+[profiles.zdr]
+model = "o3"
+model_provider = "openai"
+approval_policy = "on-failure"
+disable_response_storage = true
+```
+
+Users can specify config values at multiple levels. Order of precedence is as follows:
+
+1. custom command-line argument, e.g., `--model o3`
+2. as part of a profile, where the `--profile` is specified via a CLI (or in the config file itself)
+3. as an entry in `config.toml`, e.g., `model = "o3"`
+4. the default value that comes with Codex CLI (i.e., Codex CLI defaults to `o4-mini`)
+
 ### sandbox_permissions
 
 List of permissions to grant to the sandbox that Codex uses to execute untrusted commands:
diff --git a/codex-rs/core/Cargo.toml b/codex-rs/core/Cargo.toml
index c04bcb6a..6154d91d 100644
--- a/codex-rs/core/Cargo.toml
+++ b/codex-rs/core/Cargo.toml
@@ -58,5 +58,6 @@ openssl-sys = { version = "*", features = ["vendored"] }
 [dev-dependencies]
 assert_cmd = "2"
 predicates = "3"
+pretty_assertions = "1.4.1"
 tempfile = "3"
 wiremock = "0.6"
diff --git a/codex-rs/core/src/config.rs b/codex-rs/core/src/config.rs
index 4c815ad0..42c1684a 100644
--- a/codex-rs/core/src/config.rs
+++ b/codex-rs/core/src/config.rs
@@ -1,3 +1,4 @@
+use crate::config_profile::ConfigProfile;
 use crate::flags::OPENAI_DEFAULT_MODEL;
 use crate::mcp_server_config::McpServerConfig;
 use crate::model_provider_info::ModelProviderInfo;
@@ -8,6 +9,7 @@ use crate::protocol::SandboxPolicy;
 use dirs::home_dir;
 use serde::Deserialize;
 use std::collections::HashMap;
+use std::path::Path;
 use std::path::PathBuf;
 
 /// Maximum number of bytes of the documentation that will be embedded. Larger
@@ -16,7 +18,7 @@ use std::path::PathBuf;
 pub(crate) const PROJECT_DOC_MAX_BYTES: usize = 32 * 1024; // 32 KiB
 
 /// Application configuration loaded from disk and merged with overrides.
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, PartialEq)]
 pub struct Config {
     /// Optional override of model selection.
     pub model: String,
@@ -117,6 +119,13 @@ pub struct ConfigToml {
 
     /// Maximum number of bytes to include from an AGENTS.md project doc file.
     pub project_doc_max_bytes: Option<usize>,
+
+    /// Profile to use from the `profiles` map.
+    pub profile: Option<String>,
+
+    /// Named profiles to facilitate switching between different configurations.
+    #[serde(default)]
+    pub profiles: HashMap<String, ConfigProfile>,
 }
 
 impl ConfigToml {
@@ -176,7 +185,8 @@ pub struct ConfigOverrides {
     pub approval_policy: Option<AskForApproval>,
     pub sandbox_policy: Option<SandboxPolicy>,
     pub disable_response_storage: Option<bool>,
-    pub provider: Option<String>,
+    pub model_provider: Option<String>,
+    pub config_profile: Option<String>,
 }
 
 impl Config {
@@ -186,14 +196,16 @@ impl Config {
     pub fn load_with_overrides(overrides: ConfigOverrides) -> std::io::Result<Self> {
         let cfg: ConfigToml = ConfigToml::load_from_toml()?;
         tracing::warn!("Config parsed from config.toml: {cfg:?}");
-        Self::load_from_base_config_with_overrides(cfg, overrides)
+        let codex_dir = codex_dir().ok();
+        Self::load_from_base_config_with_overrides(cfg, overrides, codex_dir.as_deref())
     }
 
     fn load_from_base_config_with_overrides(
         cfg: ConfigToml,
         overrides: ConfigOverrides,
+        codex_dir: Option<&Path>,
     ) -> std::io::Result<Self> {
-        let instructions = Self::load_instructions();
+        let instructions = Self::load_instructions(codex_dir);
 
         // Destructure ConfigOverrides fully to ensure all overrides are applied.
         let ConfigOverrides {
@@ -202,9 +214,24 @@ impl Config {
             approval_policy,
             sandbox_policy,
             disable_response_storage,
-            provider,
+            model_provider,
+            config_profile: config_profile_key,
         } = overrides;
 
+        let config_profile = match config_profile_key.or(cfg.profile) {
+            Some(key) => cfg
+                .profiles
+                .get(&key)
+                .ok_or_else(|| {
+                    std::io::Error::new(
+                        std::io::ErrorKind::NotFound,
+                        format!("config profile `{key}` not found"),
+                    )
+                })?
+                .clone(),
+            None => ConfigProfile::default(),
+        };
+
         let sandbox_policy = match sandbox_policy {
             Some(sandbox_policy) => sandbox_policy,
             None => {
@@ -226,7 +253,8 @@ impl Config {
             model_providers.entry(key).or_insert(provider);
         }
 
-        let model_provider_id = provider
+        let model_provider_id = model_provider
+            .or(config_profile.model_provider)
             .or(cfg.model_provider)
             .unwrap_or_else(|| "openai".to_string());
         let model_provider = model_providers
@@ -259,15 +287,20 @@ impl Config {
         };
 
         let config = Self {
-            model: model.or(cfg.model).unwrap_or_else(default_model),
+            model: model
+                .or(config_profile.model)
+                .or(cfg.model)
+                .unwrap_or_else(default_model),
             model_provider_id,
             model_provider,
             cwd: resolved_cwd,
             approval_policy: approval_policy
+                .or(config_profile.approval_policy)
                 .or(cfg.approval_policy)
                 .unwrap_or_else(AskForApproval::default),
             sandbox_policy,
             disable_response_storage: disable_response_storage
+                .or(config_profile.disable_response_storage)
                 .or(cfg.disable_response_storage)
                 .unwrap_or(false),
             notify: cfg.notify,
@@ -279,8 +312,12 @@ impl Config {
         Ok(config)
     }
 
-    fn load_instructions() -> Option<String> {
-        let mut p = codex_dir().ok()?;
+    fn load_instructions(codex_dir: Option<&Path>) -> Option<String> {
+        let mut p = match codex_dir {
+            Some(p) => p.to_path_buf(),
+            None => return None,
+        };
+
         p.push("instructions.md");
         std::fs::read_to_string(&p).ok().and_then(|s| {
             let s = s.trim();
@@ -299,6 +336,7 @@ impl Config {
         Self::load_from_base_config_with_overrides(
             ConfigToml::default(),
             ConfigOverrides::default(),
+            None,
         )
         .expect("defaults for test should always succeed")
     }
@@ -377,6 +415,8 @@ pub fn parse_sandbox_permission_with_base_path(
 mod tests {
     #![allow(clippy::expect_used, clippy::unwrap_used)]
     use super::*;
+    use pretty_assertions::assert_eq;
+    use tempfile::TempDir;
 
     /// Verify that the `sandbox_permissions` field on `ConfigToml` correctly
     /// differentiates between a value that is completely absent in the
@@ -429,4 +469,173 @@ mod tests {
         let msg = err.to_string();
         assert!(msg.contains("not-a-real-permission"));
     }
+
+    /// Users can specify config values at multiple levels that have the
+    /// following precedence:
+    ///
+    /// 1. custom command-line argument, e.g. `--model o3`
+    /// 2. as part of a profile, where the `--profile` is specified via a CLI
+    ///    (or in the config file itelf)
+    /// 3. as an entry in `config.toml`, e.g. `model = "o3"`
+    /// 4. the default value for a required field defined in code, e.g.,
+    ///    `crate::flags::OPENAI_DEFAULT_MODEL`
+    ///
+    /// Note that profiles are the recommended way to specify a group of
+    /// configuration options together.
+    #[test]
+    fn test_precedence_overrides_then_profile_then_config_toml() -> std::io::Result<()> {
+        let toml = r#"
+model = "o3"
+approval_policy = "unless-allow-listed"
+sandbox_permissions = ["disk-full-read-access"]
+disable_response_storage = false
+
+# Can be used to determine which profile to use if not specified by
+# `ConfigOverrides`.
+profile = "gpt3"
+
+[model_providers.openai-chat-completions]
+name = "OpenAI using Chat Completions"
+base_url = "https://api.openai.com/v1"
+env_key = "OPENAI_API_KEY"
+wire_api = "chat"
+
+[profiles.o3]
+model = "o3"
+model_provider = "openai"
+approval_policy = "never"
+
+[profiles.gpt3]
+model = "gpt-3.5-turbo"
+model_provider = "openai-chat-completions"
+
+[profiles.zdr]
+model = "o3"
+model_provider = "openai"
+approval_policy = "on-failure"
+disable_response_storage = true
+"#;
+
+        let cfg: ConfigToml = toml::from_str(toml).expect("TOML deserialization should succeed");
+
+        // Use a temporary directory for the cwd so it does not contain an
+        // AGENTS.md file.
+        let cwd_temp_dir = TempDir::new().unwrap();
+        let cwd = cwd_temp_dir.path().to_path_buf();
+        // Make it look like a Git repo so it does not search for AGENTS.md in
+        // a parent folder, either.
+        std::fs::write(cwd.join(".git"), "gitdir: nowhere")?;
+
+        let openai_chat_completions_provider = ModelProviderInfo {
+            name: "OpenAI using Chat Completions".to_string(),
+            base_url: "https://api.openai.com/v1".to_string(),
+            env_key: Some("OPENAI_API_KEY".to_string()),
+            wire_api: crate::WireApi::Chat,
+            env_key_instructions: None,
+        };
+        let model_provider_map = {
+            let mut model_provider_map = built_in_model_providers();
+            model_provider_map.insert(
+                "openai-chat-completions".to_string(),
+                openai_chat_completions_provider.clone(),
+            );
+            model_provider_map
+        };
+
+        let openai_provider = model_provider_map
+            .get("openai")
+            .expect("openai provider should exist")
+            .clone();
+
+        let o3_profile_overrides = ConfigOverrides {
+            config_profile: Some("o3".to_string()),
+            cwd: Some(cwd.clone()),
+            ..Default::default()
+        };
+        let o3_profile_config =
+            Config::load_from_base_config_with_overrides(cfg.clone(), o3_profile_overrides, None)?;
+        assert_eq!(
+            Config {
+                model: "o3".to_string(),
+                model_provider_id: "openai".to_string(),
+                model_provider: openai_provider.clone(),
+                approval_policy: AskForApproval::Never,
+                sandbox_policy: SandboxPolicy::new_read_only_policy(),
+                disable_response_storage: false,
+                instructions: None,
+                notify: None,
+                cwd: cwd.clone(),
+                mcp_servers: HashMap::new(),
+                model_providers: model_provider_map.clone(),
+                project_doc_max_bytes: PROJECT_DOC_MAX_BYTES,
+            },
+            o3_profile_config
+        );
+
+        let gpt3_profile_overrides = ConfigOverrides {
+            config_profile: Some("gpt3".to_string()),
+            cwd: Some(cwd.clone()),
+            ..Default::default()
+        };
+        let gpt3_profile_config = Config::load_from_base_config_with_overrides(
+            cfg.clone(),
+            gpt3_profile_overrides,
+            None,
+        )?;
+        let expected_gpt3_profile_config = Config {
+            model: "gpt-3.5-turbo".to_string(),
+            model_provider_id: "openai-chat-completions".to_string(),
+            model_provider: openai_chat_completions_provider,
+            approval_policy: AskForApproval::UnlessAllowListed,
+            sandbox_policy: SandboxPolicy::new_read_only_policy(),
+            disable_response_storage: false,
+            instructions: None,
+            notify: None,
+            cwd: cwd.clone(),
+            mcp_servers: HashMap::new(),
+            model_providers: model_provider_map.clone(),
+            project_doc_max_bytes: PROJECT_DOC_MAX_BYTES,
+        };
+        assert_eq!(expected_gpt3_profile_config.clone(), gpt3_profile_config);
+
+        // Verify that loading without specifying a profile in ConfigOverrides
+        // uses the default profile from the config file.
+        let default_profile_overrides = ConfigOverrides {
+            cwd: Some(cwd.clone()),
+            ..Default::default()
+        };
+        let default_profile_config = Config::load_from_base_config_with_overrides(
+            cfg.clone(),
+            default_profile_overrides,
+            None,
+        )?;
+        assert_eq!(expected_gpt3_profile_config, default_profile_config);
+
+        let zdr_profile_overrides = ConfigOverrides {
+            config_profile: Some("zdr".to_string()),
+            cwd: Some(cwd.clone()),
+            ..Default::default()
+        };
+        let zdr_profile_config =
+            Config::load_from_base_config_with_overrides(cfg.clone(), zdr_profile_overrides, None)?;
+        assert_eq!(
+            Config {
+                model: "o3".to_string(),
+                model_provider_id: "openai".to_string(),
+                model_provider: openai_provider.clone(),
+                approval_policy: AskForApproval::OnFailure,
+                sandbox_policy: SandboxPolicy::new_read_only_policy(),
+                disable_response_storage: true,
+                instructions: None,
+                notify: None,
+                cwd: cwd.clone(),
+                mcp_servers: HashMap::new(),
+                model_providers: model_provider_map.clone(),
+                project_doc_max_bytes: PROJECT_DOC_MAX_BYTES,
+            },
+            zdr_profile_config
+        );
+
+        Ok(())
+    }
 }
diff --git a/codex-rs/core/src/config_profile.rs b/codex-rs/core/src/config_profile.rs
new file mode 100644
index 00000000..98d73bb5
--- /dev/null
+++ b/codex-rs/core/src/config_profile.rs
@@ -0,0 +1,15 @@
+use serde::Deserialize;
+
+use crate::protocol::AskForApproval;
+
+/// Collection of common configuration options that a user can define as a unit
+/// in `config.toml`.
+#[derive(Debug, Clone, Default, PartialEq, Deserialize)]
+pub struct ConfigProfile {
+    pub model: Option<String>,
+    /// The key in the `model_providers` map identifying the
+    /// [`ModelProviderInfo`] to use.
+    pub model_provider: Option<String>,
+    pub approval_policy: Option<AskForApproval>,
+    pub disable_response_storage: Option<bool>,
+}
diff --git a/codex-rs/core/src/flags.rs b/codex-rs/core/src/flags.rs
index 44198fde..e8cc973c 100644
--- a/codex-rs/core/src/flags.rs
+++ b/codex-rs/core/src/flags.rs
@@ -3,7 +3,7 @@ use std::time::Duration;
 use env_flags::env_flags;
 
 env_flags! {
-    pub OPENAI_DEFAULT_MODEL: &str = "o3";
+    pub OPENAI_DEFAULT_MODEL: &str = "o4-mini";
     pub OPENAI_API_BASE: &str = "https://api.openai.com/v1";
 
     /// Fallback when the provider-specific key is not set.
diff --git a/codex-rs/core/src/lib.rs b/codex-rs/core/src/lib.rs
index 43c97a87..c4f38026 100644
--- a/codex-rs/core/src/lib.rs
+++ b/codex-rs/core/src/lib.rs
@@ -13,6 +13,7 @@ pub mod codex;
 pub use codex::Codex;
 pub mod codex_wrapper;
 pub mod config;
+pub mod config_profile;
 mod conversation_history;
 pub mod error;
 pub mod exec;
diff --git a/codex-rs/core/src/mcp_server_config.rs b/codex-rs/core/src/mcp_server_config.rs
index 261a75d1..30845431 100644
--- a/codex-rs/core/src/mcp_server_config.rs
+++ b/codex-rs/core/src/mcp_server_config.rs
@@ -2,7 +2,7 @@ use std::collections::HashMap;
 
 use serde::Deserialize;
 
-#[derive(Deserialize, Debug, Clone)]
+#[derive(Deserialize, Debug, Clone, PartialEq)]
 pub struct McpServerConfig {
     pub command: String,
 
diff --git a/codex-rs/core/src/model_provider_info.rs b/codex-rs/core/src/model_provider_info.rs
index 969797cb..186e28d3 100644
--- a/codex-rs/core/src/model_provider_info.rs
+++ b/codex-rs/core/src/model_provider_info.rs
@@ -29,7 +29,7 @@ pub enum WireApi {
 }
 
 /// Serializable representation of a provider definition.
-#[derive(Debug, Clone, Deserialize, Serialize)]
+#[derive(Debug, Clone, Deserialize, Serialize, PartialEq)]
 pub struct ModelProviderInfo {
     /// Friendly display name.
     pub name: String,
diff --git a/codex-rs/exec/src/cli.rs b/codex-rs/exec/src/cli.rs
index 1248ef3b..dd72b3e9 100644
--- a/codex-rs/exec/src/cli.rs
+++ b/codex-rs/exec/src/cli.rs
@@ -14,6 +14,10 @@ pub struct Cli {
     #[arg(long, short = 'm')]
     pub model: Option<String>,
 
+    /// Configuration profile from config.toml to specify default options.
+    #[arg(long = "profile", short = 'p')]
+    pub config_profile: Option<String>,
+
     /// Convenience alias for low-friction sandboxed automatic execution (network-disabled sandbox that can write to cwd and TMPDIR)
     #[arg(long = "full-auto", default_value_t = false)]
     pub full_auto: bool,
diff --git a/codex-rs/exec/src/lib.rs b/codex-rs/exec/src/lib.rs
index d711388f..348bff08 100644
--- a/codex-rs/exec/src/lib.rs
+++ b/codex-rs/exec/src/lib.rs
@@ -25,6 +25,7 @@ pub async fn run_main(cli: Cli) -> anyhow::Result<()> {
     let Cli {
         images,
         model,
+        config_profile,
         full_auto,
         sandbox,
         cwd,
@@ -52,6 +53,7 @@ pub async fn run_main(cli: Cli) -> anyhow::Result<()> {
     // Load configuration and determine approval policy
     let overrides = ConfigOverrides {
         model,
+        config_profile,
         // This CLI is intended to be headless and has no affordances for asking
         // the user for approval.
         approval_policy: Some(AskForApproval::Never),
@@ -62,7 +64,7 @@ pub async fn run_main(cli: Cli) -> anyhow::Result<()> {
             None
         },
         cwd: cwd.map(|p| p.canonicalize().unwrap_or(p)),
-        provider: None,
+        model_provider: None,
     };
     let config = Config::load_with_overrides(overrides)?;
 
diff --git a/codex-rs/mcp-server/src/codex_tool_config.rs b/codex-rs/mcp-server/src/codex_tool_config.rs
index 78080795..2ddc00fb 100644
--- a/codex-rs/mcp-server/src/codex_tool_config.rs
+++ b/codex-rs/mcp-server/src/codex_tool_config.rs
@@ -22,6 +22,10 @@ pub(crate) struct CodexToolCallParam {
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub model: Option<String>,
 
+    /// Configuration profile from config.toml to specify default options.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub profile: Option<String>,
+
     /// Working directory for the session. If relative, it is resolved against
     /// the server process's current working directory.
     #[serde(default, skip_serializing_if = "Option::is_none")]
@@ -144,6 +148,7 @@ impl CodexToolCallParam {
         let Self {
             prompt,
             model,
+            profile,
             cwd,
             approval_policy,
             sandbox_permissions,
@@ -156,11 +161,12 @@ impl CodexToolCallParam {
         // Build ConfigOverrides recognised by codex-core.
         let overrides = codex_core::config::ConfigOverrides {
             model,
+            config_profile: profile,
             cwd: cwd.map(PathBuf::from),
             approval_policy: approval_policy.map(Into::into),
             sandbox_policy,
             disable_response_storage,
-            provider: None,
+            model_provider: None,
         };
 
         let cfg = codex_core::config::Config::load_with_overrides(overrides)?;
@@ -218,6 +224,10 @@ mod tests {
                 "description": "Optional override for the model name (e.g. \"o3\", \"o4-mini\")",
                 "type": "string"
               },
+              "profile": {
+                "description": "Configuration profile from config.toml to specify default options.",
+                "type": "string"
+              },
               "prompt": {
                 "description": "The *initial user prompt* to start the Codex conversation.",
                 "type": "string"
diff --git a/codex-rs/tui/src/cli.rs b/codex-rs/tui/src/cli.rs
index c260caa9..f077d267 100644
--- a/codex-rs/tui/src/cli.rs
+++ b/codex-rs/tui/src/cli.rs
@@ -17,6 +17,10 @@ pub struct Cli {
     #[arg(long, short = 'm')]
     pub model: Option<String>,
 
+    /// Configuration profile from config.toml to specify default options.
+    #[arg(long = "profile", short = 'p')]
+    pub config_profile: Option<String>,
+
     /// Configure when the model requires human approval before executing a command.
     #[arg(long = "ask-for-approval", short = 'a')]
     pub approval_policy: Option<ApprovalModeCliArg>,
diff --git a/codex-rs/tui/src/lib.rs b/codex-rs/tui/src/lib.rs
index fe4f9954..e0b6274c 100644
--- a/codex-rs/tui/src/lib.rs
+++ b/codex-rs/tui/src/lib.rs
@@ -55,7 +55,8 @@ pub fn run_main(cli: Cli) -> std::io::Result<()> {
                 None
             },
             cwd: cli.cwd.clone().map(|p| p.canonicalize().unwrap_or(p)),
-            provider: None,
+            model_provider: None,
+            config_profile: cli.config_profile.clone(),
         };
         #[allow(clippy::print_stderr)]
         match Config::load_with_overrides(overrides) {