Well-informed decisions on curricular materials can be an efficient way to boost student achievement. Prior studies have employed experimental and quasi-experimental designs to investigate the effects of textbooks on mathematics achievement. This is the first study to consider textbook effects in social studies education. Within the context of a textbook adoption cycle in Texas, we use a difference-in-differences approach with district-level administrative data and estimate the effects of adopting a state-approved textbook on social studies achievement. We find no evidence of a practically meaningful adoption effect. We conclude by highlighting the need for further high-quality research in this often-overlooked school subject area.