Evaluation of science and technology policies often poses major problems. Our focal point will be one of the most important public interventions in science and technology: public laboratories. A brief historical overview of the political context surrounding the evaluation of public applied research laboratories in Canada and in Quebec is presented as well as an examination of various methods available to evaluate these laboratories and the principal problems which confront evaluators. The paper concludes by proposing a method by which production and diffusion of knowledge of a public research laboratory can be measured. The method uses bibliometric scientometric and other techniques.