Burglars gain entrance to homes by a variety of lock-forcing and door-forcing techniques. The two most common types of home locks, mortise and key-in-the-knob locks, are inherently unsafe. Mortise locks, or locks with a large lock case fitted into door cavities, are usually insecurely anchored, while knobs with locks are easy to tear off. Although mortise locks are difficult to replace, key-in-the-knob locks may be replaced with interconnecting locksets. These locksets are two locks that must be opened with two keys but may be unlocked with one latch from the inside. Vertical deadbolt locks, which are substitutes for interconnecting locksets and auxiliary locks for mortise doors, are resistant to physical assaults but may be easily picked. Three especially effective models are described. Cylinder dead bolt and vertical dead bolt locks are other common auxiliary locks. Many otherwise sound models of these locks are poorly fastened to wooden doors and so are vulnerable to physical attack. The article's other topics include pick-resistant, high-security cylinders; window security, and methods of reinforcing existing locks. Over sixty types of locks are rated. Illustrations are included.