During the first months after birth, a child's functions begin to emerge. By age three a child is expected to have mastered the basic tasks of (1) good vegetative functioning (management of drives and impulses involved in eating and elimination), (2) perceptual organization and familiarization with the home environment and skills to orient to a new environment, (3) motor skills, (4) communication skills, (5) emotional organization, including the capacity to attach and respond to other adults and children and the capacity for love and anger, (6) sphincter control, and (7) beginning to understand time, number, and space which help to organize the present, recent past and near future. As the preschooler nears school age he learns how to adapt to separation from his mother and home, to relate to peers and a neutral teacher, and to accept rules of behavior required by a structured school atmosphere. Throughout a child's development, learning processes including Pavlovian conditioning, trial and error learning, and operant conditioning take place. Individual differences affect the complex adaptational style which evolves as the child attempts to deal with his environment. A bibliography is included. (MS)