This study explored the practices of two high school teachers of U.S. history and their students' performance on evidence-based history essays over 7 months. Data include pre- and posttest essays, interviews, observations, teacher feedback, assignments, and readings. Qualitative and quantitative comparisons of 42 students' work show that one class improved in writing evidence-based history essays whereas the other did not. Qualitative analyses of the teachers' practices suggest that different opportunities to learn to read, write, and think historically are not equally valuable. In particular, the following qualities of instruction support students' development in writing evidence-based historical essays: approaching history as evidence-based interpretation; reading historical texts and considering them as interpretations; supporting reading comprehension and historical thinking; asking students to develop interpretations and support them with evidence; and using direct instruction, guided practice, independent practice, and feedback to teach evidence-based writing. The act of writing alone is not sufficient for growth in evidence-based historical writing. (Contains 8 tables, 5 figures, and 3 notes.)