Child sex trafficking (CST) is the exchange of something of value for any sexual act with a minor. Public child welfare agencies are responsible for serving CST victims. In response to the critical need for training child welfare workers on engaging survivors of CST, we describe an innovative game-based training model used to train over 1000 workers in Maryland. The "Case-By-Case" game uses case studies to shape small group discussions, role playing, skill drills for child welfare workers to build their capacity to identify and engage survivors. Initial evaluations indicate a significant increase in knowledge and self-efficacy for training participants. The model may hold promise for social work education in this critical area, as well as for other types of professional training for social workers.