Sheldon is a practicing sociologist and has been active in research on human trafficking and transnational human smuggling activities for more than two decades. He has extensive expertise in designing and conducting large scale social surveys and specializes in prevalence estimation, survey design, sampling methodologies, and measurement development. He has gained national and international prominence leading or co-leading large-scale survey projects to estimate the prevalence of human trafficking and forced labor in the U.S. and overseas, including in Brazil, Costa Rica, Ghana, India, Kenya, Morocco, South Africa, Thailand, Tunisia, Tanzania, and Vietnam.  

Sheldon’s projects have been funded by government agencies and private foundations in the U.S. and abroad. He has written and lectured extensively on topics ranging from human trafficking to migrant smuggling and organized crime. He has been twice invited to the White House to participate in national gatherings of policymakers, advocacy groups, and researchers on combatting human trafficking.  Sheldon is a member of the organizing committee for a National Academy of Sciences forum on the latest methodologies for estimating the prevalence of modern slavery. He has authored or co-authored 14 books and edited volumes and more than 150 scholarly journal articles, book chapters, and technical reports.