Expanded school mental health (ESMH) programs, the focus of this special issue, provide comprehensive mental health care to youth in general and special education through partnerships between schools and community mental health agencies and programs. As these programs progressively develop in the United States, there is a critical need to build the research and evidence base for them. This article presents background to the national movement toward ESMH and provides an overview of articles contained in this special issue, which provide in-depth details and early research findings on diverse aspects of mental health programs in schools. Advantages of greater involvement of behavioral professionals in ESMH are discussed.