Randomized controlled trials are considered the gold standard for evaluating social work interventions. However, published reports can systematically overestimate intervention effects when researchers selectively report large and significant findings. Publication bias and other types of reporting biases can be minimized through prospective trial registration that is now an accepted part of medical research. In this article, we explain how trial registration can promote ethical and valid trials in social work, and we explain how social work researchers can register trials. We conclude that journal editors should ask authors to report trial registration numbers in all reports of randomized trials in social work.