Reforming curriculum is potentially a powerful tool for school development. Harnessing this potential calls for teacher engagement with colleagues for active professional learning, i.e., teachers’ professional agency. However, promoting teachers’ ownership and active involvement in curriculum-making provides a challenge for all levels of policy interpretation. Furthermore, variation in how teachers perceive a curriculum reform, its impact in schools and their agency within the reform are likely to occur. Yet, we still know little about this variation. We address this gap identified in prior literature by examining the individual variation and relationships within and between teachers’ sense of professional agency, perceptions of the large-scale curriculum reform impact and perceptions of overall success of the reform on a national level in the Finnish context. Teachers ( N = 1,531) from 74 schools in Finland participated in the study. Relationships between variables were examined using t-tests and ANOVAs, and latent profile analysis was used to identify professional agency profiles. The results showed that perceptions of reform impact, reform overall success and professional agency varied partly according to gender, school size, school type and teaching experience. Four profiles were identified: High sense of professional agency, Reduced collective efficacy, Active help seekers and Commitment to mutual agreement. High perceived school impact and overall reform success were linked to strong professional agency. The findings imply that development work in the context of curriculum reform can be facilitated by agentic learning in the professional community.