The lack of rigorous evaluations of intimate partner violence (IPV) programs has severely limited our knowledge about what works. However, IPV programs can be rigorously evaluated through randomized controlled trials (RCTs) conducted ethically and safely. This article provides an example of how a RCT to test an IPV preventive interventionthe Enhanced Nurse Family Partnership Study (ENFPS)was successfully implemented by a partnership of researchers and practitioners. The article concludes with some recommendations, arrived at by the researchers and practitioners on the ENFPS team, for achieving a successful collaboration thought to be essential in executing a field experiment. (Published Abstract)