The increasing number of violent and sexually explicit programs shown on cable television - on channels often viewed by young children - is a growing source of concern to parents.

The current issue of Video Magazine explores the ways in which parents can control what their children watch on cable television.The most effective way for parents to control what their kids watch is to take an active part in determining their program menu. Read the cable guide to your child, see what he watches. Cable companies have recently begun to use more detailed descriptions in their guides so phrases like "graphic violence" or "mild profanity" will help to alert parents' attention to undesirable programming.

Another way to deal with the exposure problem is a device called a lock-out box, which allows parents to lock out undesired channels on cable or broadcast TV so unauthorized viewers cannot watch them. A number of TV manufacturers now offer this lock-out feature. Alternatively, cable companies will provide one, either built into the cable box or attached to it.

There are several kinds of lock-out boxes. One type operates on a numeric password system; without punching the proper code into the lock-box, access to a locked-out channel will be denied. Others offer a padlock and key combination that prevents access.

Though the lock-out box is a sure-fire way to police children, it is no substitute for parental supervision. Child video expert Marianne Meyer advises parents to discuss television choices with their children and to offer alternative viewing options.