The wallpaper effect describes a phenomenon in which educators try to make data-drive decisions but rely exclusively on summary data (the outer layer of the wallpaper) for their information. These summary data may obscure reality--the layers and layers of systemic practices and policies that establish the conditions under which students learn. This article tells the story of a high-achieving district whose superintendent was unwilling to accept long-standing achievement gaps for Latino and black students. She established a study team that dug down to find some unexpected causes for these achievement gaps. Focus groups and interviews with students, for example, revealed that teachers and parents often discouraged qualified Latino and black students from enrolling in advanced classes, implying that they lacked the necessary "study skills" and would risk failure. In another example, the study team found that college information was posted on bulletin boards outside the advanced placement classrooms in an area that lower-level students would be unlikely to pass. By examining a wider range of data with an open mind, the school district improved outcomes for its historically underserved students.