Educators often wonder exactly how the textbooks that end up in students' hands were approved. In this article, the author explores one significant stage in the process in California, the nation's largest textbook market. The Instructional Quality Commission (IQC), an advisory board to the California Department of Education's (CDE) State Board of Education (SBE), supervises the K-8 textbook review process on an eight-year cycle. By statute, a majority of IQC members must be classroom teachers. Before 2012, the process was more consequential, as categorical funds allocated for textbooks required districts to use only adopted texts. While local school districts are no longer required to follow the SBE's final adoption recommendations, they do have to demonstrate that they have completed a similar process on their own. Since independent reviews are time-consuming and expensive, districts often rely on the SBE's final recommendations. The process described in this article is only advisory, not binding. After reviewing each panel's report, the IQC makes its own recommendation to the SBE, and the SBE, in turn, conducts its own final review. Still, the adoption process remains a key stage in the selection of suitable K-8 textbooks--one that reveals simmering debates about the role of history-social science instruction in the nation's largest state. In this article, the author shares his own experiences as a reviewer for California's 2017 adoption. He begins by briefly placing history-social science textbooks in historical context to help explain why their adoption is so contentious. Next, the author describes how the textbook adoption process works in California. Then he considers what makes the process complex, challenging, and combative. The author concludes by evaluating the significant outcomes of the review, particularly the expectations that many stakeholders have for history-social science textbooks and the problems such expectations foster.