The subject matter of the invention is a lock (1) for a motor vehicle, especially a side door lock, having a locking mechanism (2) with a catch (3) and at least one pawl (4), a release lever (10, 27), which is designed to unlock the locking mechanism (2), an actuating lever (7) for actuating the release lever (10, 27) and an inertia unit with an inertia element (12), which is designed to optionally prevent an actuating of the release lever (10, 27) depending on an actuating speed of the actuating lever (7), and the release lever (10, 27) comprises a first part (10) and a second part (27) which are designed to be coupled together.