The goal of this study was to test the effectiveness of WestEd's Reading Apprenticeship (RA) professional development program on teacher practices and student learning. The professional development is designed to teach high school teachers how to integrate subject-specific literacy instruction into their regular curricula. The CRESST researchers found that history and biology treatment teachers significantly outscored control teachers on three dimensions (reading comprehension strategies, metacognitive processes, and collaborative meaning making). History treatment teachers outperformed control teachers on an additional three dimensions (reading opportunities, support for reading engagement, and student feedback); biology treatment teachers scored higher on the adjusting instruction measure as compared to control teachers. Appended are: (1) History Teacher Assignment Rubric and Coversheets; and (2) Biology Teacher Assignment Rubric and Coversheets. (Contains 5 tables and 1 figure.)