Scholars had ignored the issue of child development prior to the various theories that developed in early 20th century. In this period, they considered children were as “small adults” with little attention accorded to their cognitive and language development (Lerner, 2002). Whereas different accounts and theories have been advanced to explain human development, there is a general agreement that human mind undergo rapid growth and change as they develop from childhood to adulthood. This affects the behavior, thinking, emotions, and personality of the child and later in adulthood. This essay examines three human development theories; social development theory advanced by Vygotsky, cognitive development theory advanced by Piaget, and psychosocial development theory advanced by Ericson.