In two of the three countries visited for this study, the host governments have passed national laws to combat trafficking in persons and enacted national action plans; however, organizations continue to face many challenges in collaborations intended to combat human trafficking. These include varying levels of government commitment to human trafficking and in the capacity to address this trafficking. International antitrafficking projects funded by the U.S. Government often lack elements that allow the projects to be monitored, so little is known about a project's impact due to difficulties in conducting evaluations. Conducting impact evaluations of antitrafficking projects is difficult due to questionable project-level estimates of the number of trafficking victims. These estimates are required in order to assess how effectively specific interventions are in reducing trafficking. A panel of experts convened to recommend ways to monitor and evaluate antitrafficking projects suggested improving information on the nature and severity of trafficking in persons and addressing monitoring and evaluation in the design of projects. Panelists suggested that projects be designed so that activities are linked to intended outcomes that have measurable indicators. In order to improve information on the nature and severity of human trafficking, panelists suggested methods that have been used to sample other hard-to-reach populations such as domestic violence victims. One suggested method is the sampling of "hot spots," i.e., an intensive search for victims in areas known to have high concentrations of trafficking victims. The study analyzed agency documents; convened an expert panel; interviewed project officials; and conducted fieldwork in Indonesia, Thailand, and Mexico. 2 tables