Using the identity lens as a theoretical framework, we studied 42 novice second career chemistry teachers, who had previously worked as chemists and participated in an alternative certification program (ACP) at a science and engineering research university. Our goal was to understand the transition process of these teachers into the teaching profession as they shape their identity and navigate through the contexts of the preparation program and the school system. Results showed that the career changers attributed their identity development to a variety of program identity resources, which shape one's identity: coursework, field experiences, and social contexts. We saw that the transition to the teaching profession was mainly due to their desire to contribute to society. Investigating three case studies, we learned that through the active participation, one's vision of the particular kind of teacher one aspires to be has developed within the unique learning environment created in the program.