Interest has been growing in the fictional portrayals of crime and the law in film and television and stems from the belief that such representations do in some way influence the ways in which the public and practitioners perceive and understand the institutions of the criminal justice system. Most criminal justice scholars believe that prison films do not carry significant levels of penal reform information. This belief is influenced not only by their extensive knowledge of the criminal justice process, but also by their understanding of film and their expectations of it. The authors posit however, that prison films can indeed influence penal reform by recognizing that the public generally lack both the factual information about what goes on inside prisons as well as the models and metaphors necessary to make sense of what information they do have. The article identifies several functions of prison film that work in relation to penal reform. These include: a revelatory function, a benchmarking function, a defense of gains function, a news/memory function, and a humanizing/empathy function. Not all prison films have these functions, and in fact some films have none. The authors argue that prison films can bring about penal reform not unilaterally, but by working in conjunction with other media, such as press campaigns. Thus the role of film is not so much the transmission of ‘factual information’ that can be derived from other sources, but rather to provide the audience with imaginative resources with which to appreciate an issue. The article looks at the influence of several films in relation to penal reform. Notes, references