Starch Professor of Psychology Jerome Kagan, a pioneering scholar of child psychology and teacher of the popular Social Analysis course, "Children and their Social Worlds," has announced he will retire from teaching at the end of the semester.

"I'll be 71 and there's a nice cycle to life," he said in an interview last night. "I think its time for younger people to move into professorship positions."

The psychology department has tenured two new professors who will join its Faculty next year.

Kagan said he plans to keep his laboratory and will serve as a research professor.

Child psychology has developed rapidly since Kagan came to Harvard in 1964. Then, several key assumptions governed study in the field. Psychologist's assumed, for instance, that the brain's development was fixed at birth. It was also thought that family relationships are wholly important in predicting the future social behavior of children. Experts in the field also assumed that culture and class had little affect on a child's chances for happiness and fulfillment.

"In the early years, there was a deep belief that what happened to the child in the early years of life fixed the child's development in a major way. We know know that's not true," Kagan said.

And only very recently have scientists realized the amazing plasticity of children's brains lasts even into adolescence.

"We now understand...in a deeper sense the correlation between maturation of the brain and the appearance of the universal milestone of development," Kagan said.