A recent Center for American Progress report, The Hidden Value of Curriculum Reform, draws bold conclusions about the high payoff of better textbooks. It finds that textbooks are rarely chosen based on evidence of effectiveness and true alignment with standards. It also finds that elementary mathematics textbook prices vary little, regardless of quality or whether or not a state recommends particular texts for adoption. While these elements of the report have merit, it then overreaches. Based on a single prior study of 1st and 2nd-grade math curricula in some high-poverty schools, it draws general conclusions about the Return on Investment (ROI) for good versus weak textbooks, ignoring key findings within the original study and also ignoring other research showing that curricular effects vary, depending on context and implementation—that is, a good book is no guarantee of benefits. The report then compares its estimated ROI for textbooks with another study’s reported ROI for other interventions, while ignoring nuances of that second study’s calculations. Overall, Hidden Value is timely and provides important insights about the need for evidence-based curriculum selection. However, its highly optimistic claims about curricular ROI could reduce support for other worthy interventions and spur simplistic comparisons of textbooks that lead to naïve conclusions about which curriculum is “best.”