Results from at least four studies of FDTCs found evidence for their effectiveness in assisting and supporting parents in entering, remaining in, and completing substance abuse treatment so they could be reunited with their children; however, different program models achieved different outcome patterns. The Pima County (Arizona) study found positive effects for treatment completion, family reunification, and reduced times to permanent placement. Two other programs showed consistent positive treatment and child welfare outcomes. Neither of these two sites produced reduced time to permanent placements. The two most successful sites were longstanding FDTCs whose models aligned closely with the core program elements supported by organizations such as the National Association of Drug Court Professionals and the Bureau of Justice Assistance. They all used an integrated judicial processing system. Although reasons for site differences were difficult to determine, the results suggest that the integrated, traditional family drug court model may be more effective than other variations. Further research is needed in order to identify and systematically test such model differences, in order to develop an understanding of what features of the FDTC are most important for achieving intended outcomes. This article summarizes the findings of completed FDTC outcome studies, including one unpublished report and two published reports. Results are also presented from a recently completed, large-scale outcome study (Worcel, Green, Furrer, Burrus, and Finigan, 2008). Four of the sites studied were in San Diego, CA; Santa Clara County, CA; Suffolk County, NY; and Washoe County, NV. 2 tables and 30 references