There is a large body of research in studies of schooling, particularly ethnographic case studies, which posits that collective action among students undermines engagement in school and contributes to educational inequality. In this paper I review studies of engagement from a social identity theory perspective. To what extent can collective action explain why some student groups are less engaged than others? I discuss four approaches to identifying social identity-related problems of engagement frequently used in prior research. While researchers often find problems of engagement among low-academic-status students, research on educational engagement has had difficulty locating the underlying causes of inequality in student engagement. Social identity theories of educational engagement are inherently theories of "collective action". I conclude that a fifth approach, large-scale observational studies of monitoring and sanctioning, provides the best framework for identifying both the prevalence of, and solutions to, this particular source of disengagement. (Contains 1 table and 2 notes.)