We report investigations of change in, and cognitive representation of young people's stereotypes of the police, in response to a police-schools liaison programme. This programme provides a real-life application of the 'conversion' model of stereotype change (in which stereotypes change radically in response to salient instances of disconfirming information). Study 1 revealed that school police officers were rated significantly more positively than the police in general, but that this view did not generalize to perceptions of the police in general. Stereotypes of the police became less positive over one year, although females were more positive than males, and school police officers were not judged typical of the category. Study 2 revealed that subjects categorized their school police officer separately from the police in general, and perceived him to share features with 'caring and welfare' professions, rather than other police officers and authority figures. Both studies converge on the limitations of the conversion model and tend to support the subtyping model (in which extremely disconfirming individuals are isolated from other group members).