Why do people say one thing and do another? Why do people behave inconsistently from one situation to another? How do people translate their beliefs and feelings into actions? This thoroughly revised and updated edition describes why and how beliefs, attitudes and personality traits influence human behaviour. Building on the strengths of the previous edition, it covers recent developments in existing theories and details new theoretical approaches to the attitude-behaviour relationships. These novel developments provide insight into the predictability - and unpredictability - of human behaviour.The book examines: recent innovations in the assessment of attitudes and personality; the implications for prediction of behaviour of these innovations; differences between spontaneous and reasoned processes; and, the most recent research on the relations between intentions and behaviour. While the book is written primarily for students and researchers in social, personality, and organizational psychology, it also has wide-reaching appeal to students, researchers and professionals in the fields of health and social welfare, marketing and consumer behaviour.