Social identity is understanding how we see ourselves and how others see us. It is shaped by our membership in social groups and the meaning given to personal attributes. This document discusses research into how social identity, personality, and social development in teenagers are interrelated. The researcher conducted interviews and observations of teenagers to understand how their social identities are formed, how they are influenced by their peers and desire to fit in, and how socializing online impacts their development. Key findings included that friendship groups and appearance are very important to teenagers' sense of identity and their social behaviors are strongly influenced by their peers and desire to be accepted.