During the last decade there has been a strong focus on making teaching into an evidence-based profession. The idea of evidence-based practice itself has been widely debated over the years and has been criticized, primarily for its positivistic assumptions. The many controversies that have arisen have tended to reinforce the dualism between qualitative and quantitative research, and seem to have made educational researchers generally reluctant to deal with the notion of evidence-based education. Following on from this, there is an inherent risk that professionals in schools will not be given enough resources to cope with the new demands made on their work. In the present thesis, the suggested way forward in this matter is to study evidence-based practice in practice. The aim of this thesis is to study the opportunities and limitations associated with the different models of evidence-based practice that have been proposed, by exploring professionals’ experiences of using evidence-based teaching strategies in the classroom. Formative assessment is used as an example to open up for an empirical approach, since it has been repeatedly identified as an evidence-based strategy. The study was conducted within the context of a local development project aimed at improving formative assessment in an upper secondary school in Sweden. In total, six teachers, who represent a mixed group of subjects, participated. To explore the teachers’ experiences in this setting, the study was based on a phenomenological approach that emphasizes collaboration between researcher and participant. The themes of lived experience that are described in the thesis invalidate the “classical model” of evidence-based practice and its expectations about how evidence can and should be used by professionals. If one considers the complexities that the teachers encountered, it is hard to see how the use of research could be made more “linear”, or how practical guidelines can raise standards of achievement. Nevertheless, it is claimed that the lived examples contribute to the present efforts to adjust the principles of evidence-based practice to educational settings. Evidence-informed practice is discussed as an alternative model and proposed as a way forward. In conclusion, the need for the evidence-based practice movement to take “critical appraisal” into account, and encourage this kind of professionalism in teachers, is deeply emphasized.