This article complicates the articulation of the achievement gap between native English speakers and English learners (ELs) as a problem rooted in English language proficiency. I challenge the institutional and popular imagination that 5.1 million ELs in the United States are “limited in English proficiency” and whose performance in school can be attributed to limited English proficiency. This argument is drawn from eighteen months of ethnographic fieldwork in a northern California High School where students identified as ELs were not a homogeneous-ability group with similar language needs. Yet there were occasions when educators echoed the concerns of education reformers and policy analysts by glossing the diversity of their EL population. In “explain failure events” the limited English proficiency of ELs was invoked to explain the academic failure of students and the school’s status as an underperforming school. I argue that the continued invocation and gloss of the diversity of ELs participates in the perpetuation of an ideology that ELs are a homogenous student population with similar educational needs. At best, the explanations offered by educators are partial descriptions of the situation of academic failure. I offer alternative explanations of academic failure by exploring the policy and cultural-ideological context of schooling.