This document provides an overview of student development theory. It discusses several influential theories including psychosocial theories proposed by Freud and Erikson, Chickering's vectors, Sanford's challenge and support theory, and student involvement/engagement theories from Astin, Tinto, and Kuh et al. Key aspects of various theories are summarized such as Erikson's psychosocial stages of development and Chickering's seven vectors. The document also outlines reasons why student development theories are useful, such as informing decision making and interpreting student behavior.