diff --git a/README.md b/README.md
index 736b9a82..c904b28a 100644
--- a/README.md
+++ b/README.md
@@ -24,6 +24,7 @@ Athena Consulting has been awarded a grant by [Atom Accelerator DAO](https://www
 - [Reading and Writing From State](https://github.com/athena-consulting/cosmwasm-by-example/tree/main/read-write-state)
 - [Response and Attributes](https://github.com/athena-consulting/cosmwasm-by-example/tree/main/responses-attributes)
 - [Cosmwasm Math Examples](https://github.com/athena-consulting/cosmwasm-by-example/tree/main/cosmwasm-math)
+- [Address Book](https://github.com/athena-consulting/cosmwasm-by-example/tree/main/address-book)
 - [Cross-Contract Instantiation](https://github.com/athena-consulting/cosmwasm-by-example/tree/main/cross-contract-instatiation)
 - [Receiving CW20 Tokens](https://github.com/athena-consulting/cosmwasm-by-example/tree/main/receiving-cw20-tokens)
 
diff --git a/address-book/.cargo/config b/address-book/.cargo/config
new file mode 100644
index 00000000..e82e5693
--- /dev/null
+++ b/address-book/.cargo/config
@@ -0,0 +1,3 @@
+[alias]
+wasm = "build --release --target wasm32-unknown-unknown"
+wasm-debug = "build --target wasm32-unknown-unknown"
diff --git a/address-book/Cargo.toml b/address-book/Cargo.toml
new file mode 100644
index 00000000..a5e0ecae
--- /dev/null
+++ b/address-book/Cargo.toml
@@ -0,0 +1,44 @@
+[package]
+name = "address-book"
+version = "0.1.0"
+authors = ["alexgduarte"]
+edition = "2021"
+
+exclude = [
+  "contract.wasm",
+  "hash.txt",
+]
+
+[lib]
+crate-type = ["cdylib", "rlib"]
+
+[profile.release]
+opt-level = 3
+debug = false
+rpath = false
+lto = true
+debug-assertions = false
+codegen-units = 1
+panic = 'abort'
+incremental = false
+overflow-checks = true
+
+[features]
+backtraces = ["cosmwasm-std/backtraces"]
+library = []
+
+[package.metadata.scripts]
+optimize = """docker run --rm -v "$(pwd)":/code \
+  --mount type=volume,source="$(basename "$(pwd)")_cache,target=/code/target \
+  --mount type=volume,source=registry_cache,target=/usr/local/cargo/registry \
+  cosmwasm/rust-optimizer:0.12.10
+"""
+
+[dependencies]
+cosmwasm-schema = "1.1.3"
+cosmwasm-std = "1.1.3"
+cw-storage-plus = "1.0.1"
+cw2 = "1.0.1"
+schemars = "0.8.10"
+serde = { version = "1.0.145", default-features = false, features = ["derive"] }
+thiserror = "1.0.31"
diff --git a/address-book/README.md b/address-book/README.md
new file mode 100644
index 00000000..d76fc3cc
--- /dev/null
+++ b/address-book/README.md
@@ -0,0 +1,72 @@
+# Address Book
+
+This example shows how a CosmWasm contract can keep a small address book in
+contract storage.
+
+The contract owner can:
+
+- Add a named contact with a validated blockchain address.
+- Remove a contact by name.
+- Transfer ownership to another address.
+
+Anyone can query:
+
+- The current owner.
+- One contact by name.
+- A paginated list of contacts.
+
+The example is intentionally simple. It focuses on common building blocks that
+new CosmWasm developers reuse often: `Item` configuration, `Map` storage,
+address validation, owner-only execute messages, and paginated range queries.
+
+## Messages
+
+Instantiate with an optional owner. If no owner is provided, the sender becomes
+the owner.
+
+```json
+{}
+```
+
+Add a contact:
+
+```json
+{
+  "add_contact": {
+    "name": "validator-one",
+    "address": "cosmos1...",
+    "note": "Primary validator address"
+  }
+}
+```
+
+Remove a contact:
+
+```json
+{
+  "remove_contact": {
+    "name": "validator-one"
+  }
+}
+```
+
+Query one contact:
+
+```json
+{
+  "contact": {
+    "name": "validator-one"
+  }
+}
+```
+
+List contacts with optional pagination:
+
+```json
+{
+  "contacts": {
+    "start_after": "validator-one",
+    "limit": 10
+  }
+}
+```
diff --git a/address-book/src/contract.rs b/address-book/src/contract.rs
new file mode 100644
index 00000000..98016843
--- /dev/null
+++ b/address-book/src/contract.rs
@@ -0,0 +1,398 @@
+#[cfg(not(feature = "library"))]
+use cosmwasm_std::entry_point;
+use cosmwasm_std::{
+    to_json_binary, Binary, Deps, DepsMut, Env, MessageInfo, Order, Response, StdResult,
+};
+use cw2::set_contract_version;
+use cw_storage_plus::Bound;
+
+use crate::error::ContractError;
+use crate::msg::{
+    ConfigResponse, ContactResponse, ContactsResponse, ExecuteMsg, InstantiateMsg, QueryMsg,
+};
+use crate::state::{Config, Contact, CONFIG, CONTACTS};
+
+const CONTRACT_NAME: &str = "crates.io:address-book";
+const CONTRACT_VERSION: &str = env!("CARGO_PKG_VERSION");
+const DEFAULT_LIMIT: u32 = 20;
+const MAX_LIMIT: u32 = 50;
+const MAX_NOTE_LENGTH: usize = 280;
+
+#[cfg_attr(not(feature = "library"), entry_point)]
+pub fn instantiate(
+    deps: DepsMut,
+    _env: Env,
+    info: MessageInfo,
+    msg: InstantiateMsg,
+) -> Result<Response, ContractError> {
+    set_contract_version(deps.storage, CONTRACT_NAME, CONTRACT_VERSION)?;
+
+    let owner = match msg.owner {
+        Some(owner) => deps.api.addr_validate(&owner)?,
+        None => info.sender.clone(),
+    };
+
+    CONFIG.save(
+        deps.storage,
+        &Config {
+            owner: owner.clone(),
+        },
+    )?;
+
+    Ok(Response::new()
+        .add_attribute("action", "instantiate")
+        .add_attribute("owner", owner))
+}
+
+#[cfg_attr(not(feature = "library"), entry_point)]
+pub fn execute(
+    deps: DepsMut,
+    _env: Env,
+    info: MessageInfo,
+    msg: ExecuteMsg,
+) -> Result<Response, ContractError> {
+    match msg {
+        ExecuteMsg::AddContact {
+            name,
+            address,
+            note,
+        } => execute_add_contact(deps, info, name, address, note),
+        ExecuteMsg::RemoveContact { name } => execute_remove_contact(deps, info, name),
+        ExecuteMsg::TransferOwnership { new_owner } => {
+            execute_transfer_ownership(deps, info, new_owner)
+        }
+    }
+}
+
+pub fn execute_add_contact(
+    deps: DepsMut,
+    info: MessageInfo,
+    name: String,
+    address: String,
+    note: Option<String>,
+) -> Result<Response, ContractError> {
+    ensure_owner(deps.as_ref(), &info)?;
+    let name = normalize_name(name)?;
+    ensure_note_length(&note)?;
+
+    if CONTACTS.may_load(deps.storage, name.clone())?.is_some() {
+        return Err(ContractError::ContactExists {});
+    }
+
+    let contact = Contact {
+        address: deps.api.addr_validate(&address)?,
+        note,
+    };
+    CONTACTS.save(deps.storage, name.clone(), &contact)?;
+
+    Ok(Response::new()
+        .add_attribute("action", "add_contact")
+        .add_attribute("name", name)
+        .add_attribute("address", contact.address))
+}
+
+pub fn execute_remove_contact(
+    deps: DepsMut,
+    info: MessageInfo,
+    name: String,
+) -> Result<Response, ContractError> {
+    ensure_owner(deps.as_ref(), &info)?;
+    let name = normalize_name(name)?;
+
+    CONTACTS.remove(deps.storage, name.clone());
+
+    Ok(Response::new()
+        .add_attribute("action", "remove_contact")
+        .add_attribute("name", name))
+}
+
+pub fn execute_transfer_ownership(
+    deps: DepsMut,
+    info: MessageInfo,
+    new_owner: String,
+) -> Result<Response, ContractError> {
+    ensure_owner(deps.as_ref(), &info)?;
+    let new_owner = deps.api.addr_validate(&new_owner)?;
+
+    CONFIG.save(
+        deps.storage,
+        &Config {
+            owner: new_owner.clone(),
+        },
+    )?;
+
+    Ok(Response::new()
+        .add_attribute("action", "transfer_ownership")
+        .add_attribute("new_owner", new_owner))
+}
+
+#[cfg_attr(not(feature = "library"), entry_point)]
+pub fn query(deps: Deps, _env: Env, msg: QueryMsg) -> StdResult<Binary> {
+    match msg {
+        QueryMsg::Config {} => to_json_binary(&query_config(deps)?),
+        QueryMsg::Contact { name } => to_json_binary(&query_contact(deps, name)?),
+        QueryMsg::Contacts { start_after, limit } => {
+            to_json_binary(&query_contacts(deps, start_after, limit)?)
+        }
+    }
+}
+
+fn query_config(deps: Deps) -> StdResult<ConfigResponse> {
+    let config = CONFIG.load(deps.storage)?;
+
+    Ok(ConfigResponse {
+        owner: config.owner.to_string(),
+    })
+}
+
+fn query_contact(deps: Deps, name: String) -> StdResult<ContactResponse> {
+    let name = normalize_name_for_query(name);
+    let contact = CONTACTS.load(deps.storage, name.clone())?;
+
+    Ok(contact_response(name, contact))
+}
+
+fn query_contacts(
+    deps: Deps,
+    start_after: Option<String>,
+    limit: Option<u32>,
+) -> StdResult<ContactsResponse> {
+    let limit = limit.unwrap_or(DEFAULT_LIMIT).min(MAX_LIMIT) as usize;
+    let start = start_after
+        .map(normalize_name_for_query)
+        .map(Bound::exclusive);
+
+    let contacts = CONTACTS
+        .range(deps.storage, start, None, Order::Ascending)
+        .take(limit)
+        .map(|item| item.map(|(name, contact)| contact_response(name, contact)))
+        .collect::<StdResult<Vec<_>>>()?;
+
+    Ok(ContactsResponse { contacts })
+}
+
+fn ensure_owner(deps: Deps, info: &MessageInfo) -> Result<(), ContractError> {
+    let config = CONFIG.load(deps.storage)?;
+
+    if info.sender != config.owner {
+        return Err(ContractError::Unauthorized {});
+    }
+
+    Ok(())
+}
+
+fn normalize_name(name: String) -> Result<String, ContractError> {
+    let name = normalize_name_for_query(name);
+
+    if name.is_empty() {
+        return Err(ContractError::EmptyName {});
+    }
+
+    Ok(name)
+}
+
+fn normalize_name_for_query(name: String) -> String {
+    name.trim().to_ascii_lowercase()
+}
+
+fn ensure_note_length(note: &Option<String>) -> Result<(), ContractError> {
+    if note.as_ref().map(|note| note.len()).unwrap_or_default() > MAX_NOTE_LENGTH {
+        return Err(ContractError::NoteTooLong {});
+    }
+
+    Ok(())
+}
+
+fn contact_response(name: String, contact: Contact) -> ContactResponse {
+    ContactResponse {
+        name,
+        address: contact.address.to_string(),
+        note: contact.note,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use cosmwasm_std::testing::{mock_dependencies, mock_env, mock_info};
+    use cosmwasm_std::{coins, from_json};
+
+    use super::*;
+
+    #[test]
+    fn instantiate_uses_sender_as_default_owner() {
+        let mut deps = mock_dependencies();
+        let info = mock_info("owner", &coins(1, "uatom"));
+
+        instantiate(
+            deps.as_mut(),
+            mock_env(),
+            info,
+            InstantiateMsg { owner: None },
+        )
+        .unwrap();
+
+        let response: ConfigResponse =
+            from_json(&query(deps.as_ref(), mock_env(), QueryMsg::Config {}).unwrap()).unwrap();
+        assert_eq!(response.owner, "owner");
+    }
+
+    #[test]
+    fn owner_can_add_and_query_contact() {
+        let mut deps = mock_dependencies();
+        instantiate(
+            deps.as_mut(),
+            mock_env(),
+            mock_info("owner", &[]),
+            InstantiateMsg { owner: None },
+        )
+        .unwrap();
+
+        execute(
+            deps.as_mut(),
+            mock_env(),
+            mock_info("owner", &[]),
+            ExecuteMsg::AddContact {
+                name: "Validator One".to_string(),
+                address: "validator".to_string(),
+                note: Some("primary validator".to_string()),
+            },
+        )
+        .unwrap();
+
+        let response: ContactResponse = from_json(
+            &query(
+                deps.as_ref(),
+                mock_env(),
+                QueryMsg::Contact {
+                    name: "validator one".to_string(),
+                },
+            )
+            .unwrap(),
+        )
+        .unwrap();
+
+        assert_eq!(response.name, "validator one");
+        assert_eq!(response.address, "validator");
+        assert_eq!(response.note, Some("primary validator".to_string()));
+    }
+
+    #[test]
+    fn non_owner_cannot_add_contact() {
+        let mut deps = mock_dependencies();
+        instantiate(
+            deps.as_mut(),
+            mock_env(),
+            mock_info("owner", &[]),
+            InstantiateMsg { owner: None },
+        )
+        .unwrap();
+
+        let error = execute(
+            deps.as_mut(),
+            mock_env(),
+            mock_info("visitor", &[]),
+            ExecuteMsg::AddContact {
+                name: "friend".to_string(),
+                address: "friend".to_string(),
+                note: None,
+            },
+        )
+        .unwrap_err();
+
+        assert_eq!(error, ContractError::Unauthorized {});
+    }
+
+    #[test]
+    fn contacts_query_is_paginated() {
+        let mut deps = mock_dependencies();
+        instantiate(
+            deps.as_mut(),
+            mock_env(),
+            mock_info("owner", &[]),
+            InstantiateMsg { owner: None },
+        )
+        .unwrap();
+
+        for name in ["alice", "bob", "carol"] {
+            execute(
+                deps.as_mut(),
+                mock_env(),
+                mock_info("owner", &[]),
+                ExecuteMsg::AddContact {
+                    name: name.to_string(),
+                    address: format!("{name}-addr"),
+                    note: None,
+                },
+            )
+            .unwrap();
+        }
+
+        let response: ContactsResponse = from_json(
+            &query(
+                deps.as_ref(),
+                mock_env(),
+                QueryMsg::Contacts {
+                    start_after: Some("alice".to_string()),
+                    limit: Some(2),
+                },
+            )
+            .unwrap(),
+        )
+        .unwrap();
+
+        let names: Vec<String> = response
+            .contacts
+            .into_iter()
+            .map(|contact| contact.name)
+            .collect();
+        assert_eq!(names, vec!["bob".to_string(), "carol".to_string()]);
+    }
+
+    #[test]
+    fn owner_can_remove_contact() {
+        let mut deps = mock_dependencies();
+        instantiate(
+            deps.as_mut(),
+            mock_env(),
+            mock_info("owner", &[]),
+            InstantiateMsg { owner: None },
+        )
+        .unwrap();
+
+        execute(
+            deps.as_mut(),
+            mock_env(),
+            mock_info("owner", &[]),
+            ExecuteMsg::AddContact {
+                name: "friend".to_string(),
+                address: "friend".to_string(),
+                note: None,
+            },
+        )
+        .unwrap();
+        execute(
+            deps.as_mut(),
+            mock_env(),
+            mock_info("owner", &[]),
+            ExecuteMsg::RemoveContact {
+                name: "friend".to_string(),
+            },
+        )
+        .unwrap();
+
+        let response: ContactsResponse = from_json(
+            &query(
+                deps.as_ref(),
+                mock_env(),
+                QueryMsg::Contacts {
+                    start_after: None,
+                    limit: None,
+                },
+            )
+            .unwrap(),
+        )
+        .unwrap();
+
+        assert!(response.contacts.is_empty());
+    }
+}
diff --git a/address-book/src/error.rs b/address-book/src/error.rs
new file mode 100644
index 00000000..b74ac52d
--- /dev/null
+++ b/address-book/src/error.rs
@@ -0,0 +1,20 @@
+use cosmwasm_std::StdError;
+use thiserror::Error;
+
+#[derive(Error, Debug, PartialEq)]
+pub enum ContractError {
+    #[error("{0}")]
+    Std(#[from] StdError),
+
+    #[error("Unauthorized")]
+    Unauthorized {},
+
+    #[error("Contact already exists")]
+    ContactExists {},
+
+    #[error("Contact name cannot be empty")]
+    EmptyName {},
+
+    #[error("Contact note cannot be longer than 280 characters")]
+    NoteTooLong {},
+}
diff --git a/address-book/src/lib.rs b/address-book/src/lib.rs
new file mode 100644
index 00000000..e5ff7237
--- /dev/null
+++ b/address-book/src/lib.rs
@@ -0,0 +1,6 @@
+pub mod contract;
+pub mod error;
+pub mod msg;
+pub mod state;
+
+pub use crate::error::ContractError;
diff --git a/address-book/src/msg.rs b/address-book/src/msg.rs
new file mode 100644
index 00000000..a9a3d08f
--- /dev/null
+++ b/address-book/src/msg.rs
@@ -0,0 +1,52 @@
+use cosmwasm_schema::{cw_serde, QueryResponses};
+
+#[cw_serde]
+pub struct InstantiateMsg {
+    pub owner: Option<String>,
+}
+
+#[cw_serde]
+pub enum ExecuteMsg {
+    AddContact {
+        name: String,
+        address: String,
+        note: Option<String>,
+    },
+    RemoveContact {
+        name: String,
+    },
+    TransferOwnership {
+        new_owner: String,
+    },
+}
+
+#[cw_serde]
+#[derive(QueryResponses)]
+pub enum QueryMsg {
+    #[returns(ConfigResponse)]
+    Config {},
+    #[returns(ContactResponse)]
+    Contact { name: String },
+    #[returns(ContactsResponse)]
+    Contacts {
+        start_after: Option<String>,
+        limit: Option<u32>,
+    },
+}
+
+#[cw_serde]
+pub struct ConfigResponse {
+    pub owner: String,
+}
+
+#[cw_serde]
+pub struct ContactResponse {
+    pub name: String,
+    pub address: String,
+    pub note: Option<String>,
+}
+
+#[cw_serde]
+pub struct ContactsResponse {
+    pub contacts: Vec<ContactResponse>,
+}
diff --git a/address-book/src/state.rs b/address-book/src/state.rs
new file mode 100644
index 00000000..0a999fd5
--- /dev/null
+++ b/address-book/src/state.rs
@@ -0,0 +1,17 @@
+use cosmwasm_schema::cw_serde;
+use cosmwasm_std::Addr;
+use cw_storage_plus::{Item, Map};
+
+#[cw_serde]
+pub struct Config {
+    pub owner: Addr,
+}
+
+#[cw_serde]
+pub struct Contact {
+    pub address: Addr,
+    pub note: Option<String>,
+}
+
+pub const CONFIG: Item<Config> = Item::new("config");
+pub const CONTACTS: Map<String, Contact> = Map::new("contacts");