Teachers' lack of knowledge abound computational thinking (CT) and limited opportunities to incorporate CT in existing curricula pose unique challenges at the elementary level. Despite the crucial role of professional development (PD) in preparing elementary school teachers to integrate CT in classroom instruction, there is little research documenting PD programs that focus on integration in literacy and mathematics compared to other subject areas. In this work, we present a PD program that integrates CT with disciplinary content to support teachers as they integrate CT with literacy and mathematics in elementary school classrooms. Using data from multiple sources, we present findings from two case studies to examine the impact of PD on teachers' integration of CT with content in lesson planning and implementation. Findings have implications related to the integration of CT in elementary school and teacher PD.