It first describes the mechanism of "warded" locks, which is the old type of lock used in homes 50 years ago. It has a large simple keyhole and uses a large simple key. The easiest way to open one of these locks is with a pass key, which can be bought or made. A pass key can be made from any of the warded lock keys by filing it so it will not strike any of the wards as it is turned in the lock. An illustration shows how to file a pass key. Warded padlocks are described as well, along with how to file a pass key for them. "Lever tumbler" locks are then described, and the "picking" of such locks of varying complexity is described. The booklet moves next to "disc" and "wafer" tumbler locks. "Picking" a disc tumbler lock requires pulling all the discs that compose the locking mechanism down into the core so the core is free to turn and the lock can open. This is done with two tools whose characteristics are described and illustrated with drawings. Pin tumbler locks -- one of the best, most secure, and most widely used type of locks -- is then described. It receives its name from the small pins it uses to operate. "Picking" this lock requires aligning the pins so that they meet, or break, at the top edge of the core. The tools required to achieve this are described and illustrated. The final section of the booklet addresses combination locks and how to gain entry without keys or lockpicking, i.e., with the use of credit cards, a knife or screwdriver, drill, or stiff wire.