Personality is always associated with persons in a social setting. It changes with the person & the society. For example – When a baby is born, it does not really have a distinct personality of its own. Most of them look similar & behave similarly, but as it grows, emerges a new person. The reason is, as it grows up, the surrounding factors shape up the personality. The word personality is derived from the Greek word “Persona” means Mask. So the study of personality can be understood as the study of invisible “masks” that people wear. According to Kilpatrick – Personality is a person among persons. There is no personality of one man on a desert island. According to Murray – A person’s personality is like all other persons, like some other persons & like no other person. According to Psychologists, personality is our external appearances & inner awareness. According to MGT, personality is the sum total of ways in which an individual reacts & interacts with others. Determinants of Personality are: Biological factors Cultural factors Family factors Social factors Situational factors Theories of Personality are:- psychoanalytical theory Socio-psychological Extroverts & Introverts Type theory Self theory Trait theory Social learning Johari Window Transactional Analysis Personality can be measured through different subjective tools such as - protective tests, behavioral measures & self-report questionnaires.