There is growing attention to the potential for developing professional learning experiences for content area teachers to infuse computational thinking (CT), which refers to the set of problem-solving practices related to the computer science discipline, into their classrooms. Although research has begun to document professional learning models and supports for CT infusion, an understudied area for both research and practice is how in-service teachers come to lead CT infusion efforts through determining curriculum, supporting their colleagues, and designing school and district-wide programs, once the professional development (PD) and related learning experiences are over. In this paper, we document findings from the final year of a five-year PD project, in which a subset of middle and high school content area teachers and teacher teams (n=12) proposed, designed, and carried out their own CT infusion projects. Using a practitioner inquiry framework, we analyze teachers' choices in project types (curriculum development, teacher PD, and activities designed to connect in-school and informal learning), motivating factors for applying for the grant, their inquiry processes, and their perceptions of project impact. We discuss suggestions for supporting teacher-led CT infusion, including taking incremental approaches that develop teacher knowledge over time, building both discipline-specific and interdisciplinary teacher communities, and engaging multiple stakeholders to build the culture necessary for CT infusion. We conclude with general implications for creating structures to sustain and extend researcher-practitioner partnerships.