Recent education reform has emphasized the importance of teacher learning in improving classroom instruction and raising student achievement. This article focuses on teachers' learning opportunities, including formal professional development and on-the-job learning that occurs through interactions with colleagues. Using data from 30 elementary schools in a mid-sized urban school district, the authors concurrently explore the relationships between teachers' formal professional development and on-the-job learning opportunities and instructional change. Results suggest that formal professional development and on-the-job opportunities to learn are both significantly associated with changes in teachers' instructional practice in mathematics and English language arts.