The aim of this study was to investigate the production of knowledge that can emerge in the use of Practice Research by Mirror method. This by finding out what it is in the practical work that leads to the production of knowledge and how knowledge production takes form. The empirical data that form the basis for this study is recorded group within the Mirror method discussions and a focus group interview with social workers who participated in the discussions. Those who have participated are social workers with experience from working with financial aid support and only real cases have been used in the discussions. The results have been analyzed according to Lipsky's theory of street-level bureaucracy and their discretion and Fook and Gardner´s theory of critical reflection. The results of the study show that evaluation and review of a difficult work using critical reflection as a tool and a reflexive approach leads to the development of the practical work.