In this quasi-experimental study, 608 fourth-, fifth-, and sixth-grade students explored 5 historical investigations. In the experimental condition, teachers used a cognitive apprenticeship model to teach students historical reading and writing strategies. Comparison teachers used the same materials to deliver a business-as-usual form of instruction. Random assignment was at the individual level for fourth and fifth graders and at the classroom level for sixth graders. After controlling for gender, ethnicity, and pretest scores, the findings indicated that experimental students outperformed their peers in control classrooms on measures of essay length (ES = 0.25), holistic writing quality (ES = 0.59), and argumentative historical writing (ES = 0.67). Differences in students' argumentative historical writing remained after six weeks (ES = 0.71). Finally, students with disabilities as well as those who did not meet annual reading proficiency benchmarks on state-administered assessments all benefited from experimental instruction. These results suggest that with appropriate supports and the opportunity to engage in meaningful historical content, students in fourth through sixth grade can analyze primary and secondary source documents and write evidence-based historical arguments.