This report presents findings from a review and analysis of literature on the importance, effectiveness, and availability of support services for participants in job training programs in the United States. It assesses current knowledge about these services by examining reports on training and education programs, as well as literature on the importance of supportive services for low-income individuals in general. The report also examines the availability of supportive services in the workforce development system, funding sources for these services, and common barriers to employment and training--such as lack of access to child care, transportation, and stable housing--that these supports can address. The report was informed by interviews with 25 experts on workforce development and supportive services. It is a part of a larger Institute for Women's Policy Research project on the role of supportive services in promoting job training and employment success that is funded by the Walmart Foundation.