The progress and effects of a collaborative study group as a method of job-embedded professional development were studied. Eight high school teachers representing a variety of disciplines and the author (a literacy specialist) met monthly as a collaborative group for one school year to investigate materials and methods for literacy strategy instruction in content area classes. Participation in this collaborative study group had considerable positive and sustained influence on the teachers' instructional practices, their knowledge and beliefs, and on their students' achievement, all related to content literacy. The results of this experience suggest that the development of opportunities for long-term teacher collaborative interactions is an important and effective professional learning option for secondary teachers attempting to integrate literacy strategies and content instruction. (Contains 2 tables and 3 figures.)