Educational gender gap research tries to explain the differential achievement of boys and girls at secondary school, which manifests in many western countries. Several explanatory frameworks are used for this purpose, such as masculinities theory. In this review article, the history of educational gender gap research in Anglo-Saxon literature and problems with the contemporary approach are discussed. It is argued that gender identity theory could prove valuable both in furthering educational gender gap research and mitigating several problems with masculinities theory. To this end, an overview of the history and recent developments in gender identity theory is given. The scarce research combining educational gender gap research with gender identity theory is reviewed. Possible contributions, assets and research questions from gender identity theory to educational gender gap research are discussed.