The Truancy Assessment and Service Centers (TASC) program is an evidencebased elementary school truancy intervention that utilizes specially trained case managers to rapidly assess and address the underlying causes of truancy. This study explored case manager perspectives to gain a deeper understanding of the effectiveness of the TASC program. The authors conducted in-depth structured interviews with six TASC case managers using grounded theory methods. The overarching theme indicated that the case manager was the primary agent of change. As such, intervention effectiveness was maximized if the case managers were committed to their clients' families, assisted them in building a collaborative support network, and helped them to overcome barriers that adversely affected the treatment process. Findings also suggested that unsuccessful program outcomes may be related to high caseloads and staff shortages. This article concludes with a discussion on policy and practice implications for school social workers.