Imagination can be a 3-year-old's best ally or worst enemy. From imaginary playmates to scary nighttime monsters, the world of pretend is a very important and real part of growing up.

According to family psychologist John Rosemond, contributing editor to Better Homes and Gardens magazine, imaginative play marks an important stage in a child's intellectual development. Pretending exercises a child's abstract thinking skills and encourages independent play, initiative, resourcefulness and self-sufficiency.Most important, imaginative play is the force behind creativity.

But just as learning to walk involves falling down, learning to control one's imagination involves coming to terms with its darker side. While 3-year-olds delight in inventing imaginary playmates, they also scare themselves silly by inventing monsters and ghosts.

Creative play often evokes the best part of a youngster's fancy, the imaginary playmate. Usually, children who have or have had imaginary playmates are more successful at making and keeping friends. They're not only better able to give and take, they're more fun loving. Children's invisible friends help them improve their social skills.

Children invest a considerable amount of security in their imaginary friends. Consequently, a parent should never suggest a child's imaginary friends aren't real. To the child, if something can be imagined, then that something truly exists.

Unless it's absolutely necessary, don't disturb a child who is playing with imaginary friends. If it is necessary, have the utmost respect for the child's "guest."

Though a child's imagination may produce great playmates by day, by night the same visionary youngster may conjure up some very scary monsters.

Young children usually cannot separate fact from fiction, nor can they comprehend that words exist for things that don't. A child can "see" a monster, whether parents do or not.

Parents often interpret this fear to be a sign of some deeper emotional problem. So they try to offer protection, perhaps by lying down with their child until he or she falls asleep.

But this may have the opposite effect, reinforcing the idea that there is something to fear. Trying to reason away a fear won't work either. Logic and imagination exist on two separate, incompatible wavelengths.

Monsters often disappear quickly when parents teach their children creative ways of controlling feelings of helplessness. For example, the parents of one 3-year-old girl fashioned a "magic wand" which she used to "zap" the monster that came out of her closet at night. Within a few weeks, the frustrated monster packed its bags and departed.