**A Mathematician's Lament**, often referred to informally as **Lockhart's Lament**, is a short book on the pedagogics and philosophy of mathematics by Paul Lockhart, originally a research mathematician but for many years a math teacher at Saint Ann's School in Brooklyn, New York. Characterized as a strongly worded opinion piece arguing for an aesthetic, intuitive and heuristic approach to teaching and the importance of mathematics teaching reforms, the book frames learning mathematics as an artistic and imaginative pursuit which is not reflected at all in the way the subject is taught in the American educational system.

The book was developed from a 25-page essay that was written in 2002, originally circulated in typewritten manuscript copies, and subsequently on the Internet.