ABSTRACT In the past few decades, a large body of research has been conducted on pedagogical content knowledge (PCK), but further empirical and theoretical studies are needed to enhance our understanding of PCK development. This study aimed to describe the development of PCK of evolution in a group of biology teachers using a modified version of the refined consensus model (Mixed Model), including the five components of PCK from the model elaborated by Magnusson et al. (1999). The qualitative research design involved multiple study cases, including semi-structured interviews and lesson plan meetings. A collective PCK (cPCK) map was generated via content representation interviews with six expert biology teachers and scholars. The ideas expressed by three or more experts were then included in the cPCK map, which was used to assess the personal PCK (pPCK) development of a different group of seven biology schoolteachers using three traits: map area, map shape, and the identity of the concepts included in the map. The findings show that the development of teachers’ pPCK was mainly due to the increase in the map area resulting from the inclusion of new concepts belonging to knowledge of students learning and to the knowledge associated with strategies.