diff --git a/src/frame/base.rs b/src/frame/base.rs
index 97552cc..cee61bb 100644
--- a/src/frame/base.rs
+++ b/src/frame/base.rs
@@ -1,3 +1,19 @@
+//! Core data-frame structures such as [`Frame`] and [`RowIndex`].
+//!
+//! The [`Frame`] type stores column-labelled data with an optional row index
+//! and builds upon the [`crate::matrix::Matrix`] type.
+//!
+//! # Examples
+//!
+//! ```
+//! use rustframe::frame::{Frame, RowIndex};
+//! use rustframe::matrix::Matrix;
+//!
+//! let data = Matrix::from_cols(vec![vec![1, 2], vec![3, 4]]);
+//! let frame = Frame::new(data, vec!["L", "R"], Some(RowIndex::Int(vec![10, 20])));
+//! assert_eq!(frame.columns(), &["L", "R"]);
+//! assert_eq!(frame.index(), &RowIndex::Int(vec![10, 20]));
+//! ```
 use crate::matrix::Matrix;
 use chrono::NaiveDate;
 use std::collections::HashMap;
diff --git a/src/frame/mod.rs b/src/frame/mod.rs
index ced467c..e5e94b0 100644
--- a/src/frame/mod.rs
+++ b/src/frame/mod.rs
@@ -1,3 +1,21 @@
+//! High-level interface for working with columnar data and row indices.
+//!
+//! The [`Frame`](crate::frame::Frame) type combines a matrix with column labels and a typed row
+//! index, similar to data frames in other data-analysis libraries.
+//!
+//! # Examples
+//!
+//! ```
+//! use rustframe::frame::{Frame, RowIndex};
+//! use rustframe::matrix::Matrix;
+//!
+//! // Build a frame from two columns labelled "A" and "B".
+//! let data = Matrix::from_cols(vec![vec![1.0, 2.0], vec![3.0, 4.0]]);
+//! let frame = Frame::new(data, vec!["A", "B"], None);
+//!
+//! assert_eq!(frame["A"], vec![1.0, 2.0]);
+//! assert_eq!(frame.index(), &RowIndex::Range(0..2));
+//! ```
 pub mod base;
 pub mod ops;
 
diff --git a/src/frame/ops.rs b/src/frame/ops.rs
index 1c3254b..6030ce1 100644
--- a/src/frame/ops.rs
+++ b/src/frame/ops.rs
@@ -1,3 +1,16 @@
+//! Trait implementations that allow [`Frame`] to reuse matrix operations.
+//!
+//! These modules forward numeric and boolean aggregation methods from the
+//! underlying [`Matrix`](crate::matrix::Matrix) type so that they can be called
+//! directly on a [`Frame`].
+//!
+//! ```
+//! use rustframe::frame::Frame;
+//! use rustframe::matrix::{Matrix, SeriesOps};
+//!
+//! let frame = Frame::new(Matrix::from_cols(vec![vec![1.0, 2.0]]), vec!["A"], None);
+//! assert_eq!(frame.sum_vertical(), vec![3.0]);
+//! ```
 use crate::frame::Frame;
 use crate::matrix::{Axis, BoolMatrix, BoolOps, FloatMatrix, SeriesOps};