This study aims to assess the effectiveness of reciprocal peer observation (RPO) as a form of professional collaboration among teachers in enhancing their perceptions of teacher collaboration within a school setting. The Teacher Collaboration Perceptions Questionnaire (TCPQ) was specifically designed and validated for this purpose, using exploratory factor analysis and confirmatory factor analysis. The study employed a longitudinal observational design, with 400 teachers in a pre/post-test study. The impact of RPO was examined on three dimensions related to professional collaboration: collaborative school culture, collective agency and teachers' attitudes towards collaboration. The results revealed that participants' perceptions of collaboration improved significantly after the implementation of RPO. The study confirms the utility of RPO as a professional collaborative practice that can foster changes in teachers' perceptions of the collaborative school culture, teachers' sense of collective agency and teachers' preference for collaboration over individual work. The study concludes with a discussion of its educational implications.