This study focused on a professional development program for secondary school science teachers at the Musée de la civilisation [Museum of Civilization] in Québec City, Québec. We followed a group of four science teachers throughout their immersion in the museum’s collaborative activities in order to describe and better understand how this experience changed their teaching practices and their relationships with museums. The immersion of science teachers in museums can be considered a catalyst for learning, for acquiring new ways of understanding the world, and for changing practices of teaching and learning science. In this chapter we describe the participating teachers’ perspectives in this 24-month museum program. A qualitative–interpretative research design emphasizing an inductive approach was used in a study from the perspective of Wenger’s social theory of learning. Learning thus has four dimensions—meaning, practice, community, and identity—that are closely interrelated and mutually determining. Results shed light on the four dimensions and how participation in collaborative activities can transform individuals.