<p>TPACK (technological pedagogical content knowledge) has been widely used as a framework for understanding and creating teacher professional development experiences with technology, including teacher learning about programming and computational thinking (CT), which refers to the set of problem-solving practices inherent to the computer science discipline. However, one persistent gap in the knowledge base is the need for research that examines teachers’ development of new pedagogical practices over an extended period. This study contributes a longitudinal perspective on teacher learning about computational thinking in relation to three TPACK domains: pedagogical content knowledge, technological content knowledge, and technological pedagogical content knowledge. Qualitative data from a five-year study of teachers’ CT integration, including interviews, surveys, programming products, pedagogical artifacts, and practitioner research projects, were analyzed to unpack how two case study teachers (secondary math and science) came to understand CT and coding concepts, as well as how they utilized CT-infused teaching practices in their classrooms. Findings suggest that as teachers developed clear understandings of CT and more sophisticated knowledge of programming concepts, they were able to design scaffolded and sequential CT learning experiences for students and colleagues.</p>