The history of school social work in the United States is nearly as old as the history of public education. Despite the presence of social workers in schools throughout this time, the profession has generally been established within schools through confluence of interests with broader social and educational movements or policy windows. These policy windows have brought opportunities for school social work but also constrained practice in many complex ways. This article will explore the history of school social work using the policy window lens to investigate how dominant practice models have been shaped. It will also describe recent movements in educational policy and practice that suggest increased openness to comprehensive approaches to student support. Given the promise of these changes, recommendations for how policy can support an integrated approach to social work practice will be advanced.