Most stereotypes of youth depict them as problematic. Yet, the effects of those representations on behaviour are not understood. The nine studies conducted for this thesis investigated stereotypic beliefs about youth. This thesis aimed to specify the range of stereotypic beliefs about youth, the sources of those beliefs, and the consequences of those beliefs for adults' and young people's behaviour. Chapter' 1 reviews the stereotype literature and provides information about our current understanding of stereotypic beliefe about youth. It also highlights the limitations of existing research and presents the rationale for this program of research.Chapter 2 presents studies 1 to 4, which explored the breadth in the content of four sets of stereotypic beliefs about youth. Study 1 investigated adults'knowledge of the cultural stereotype of youth and Study 2A specified adults' personal beliefs about youth. Adults' knowledge of the cultural stereotype was shown to consist ofvery negative content, although their personal beliefs were bothpositive and negative in content...