This document summarizes several theories of personality development. It discusses definitions of personality from various researchers and outlines five major theories: Abraham Maslow's hierarchy of needs theory which describes how humans are motivated to fulfill basic needs; Albert Bandura's social learning theory which proposes behavior is learned through observation and modeling; John Watson's behavioral theory stating all behavior is learned through conditioning and stimuli; George Kelly's cognitive theory that personality is explained by an individual's unique thoughts and interpretations; and John Bowlby's attachment theory examining the dynamics of long-term relationships.