The purpose of this paper is to explore the construction of the professional identity of Alex (a pseudonym), a physical educator in charge of sport and physical activity in a Spanish prison. To this end, we used a biographical-dialectic perspective based mainly on interviews especially focused on prior experiences, contextual resources and the micropolitical strategies Alex used in his workplace. The search for better job conditions and professional recognition mediated the strategies he used during the daily negotiation of his professional identity. Yet, this identity was also constructed in a dialogue between his experiences in sport and the performance discourse present at the macro-social level. This study exemplifies a particular, yet not unique case of professional socialization that helps illuminate the (re)construction of identity of those physical activity and sport professionals who work in marginal contexts