Attitude research began in the early part of the 20th century, and remains a significant interest for some social psychologists. Like many areas of psychology, interest in attitudes has taken different approaches at different times, reflecting the dominating zeitgeist, and the social concerns of scientists in general and psychologists in particular. One of the accepted characteristics of attitudes is that they involve either positive or negative affect- that is, feelings of either liking or disliking. This chapter looks at some of the general approaches that researchers have taken to attitude measurement. Cognitive dissonance can be a powerful factor in attitude change. The theory of reasoned action emphasises the importance of intention in analysing discrepancies between attitudes and behaviour. It was later modified into the theory of planned behaviour. Persuasion is also dependent on involvement, which may be of three types: value-relevant involvement, impression-relevant involvement and outcome-relevant involvement.