Human service evaluators have successfully conducted many studies examining the development, implementation and impact of programs on families. However, gaining a comprehensive picture of services and supports that clients receive may be difficult when parent agencies refer to outside resources. This think tank provides a forum to discuss how to define and measure the 'black box' of external services considered a key contributor to the success of family outcomes. First, efforts to collect data on externally referred services are briefly described, this is followed by breakout discussions that allow attendees to share their own experiences in identifying key services, developing measures, and collecting services data. The goal of the session is to facilitate a discussion of the values inherent in deciding what and how services data should be collected as well coming away from the session with strategies that could enhance future evaluation efforts in this area. #2011Conference #SocialWork #HumanServicesEvaluation