Return on investment (ROI) analysis of state vocational rehabilitation (VR) agencies is a way to evaluate the efficacy of a VR program. Several different formulas can be used to make this comparison, but all compare program benefits with costs in some manner. For every dollar spent on services provided to a VR client, the ROI reports how many extra dollars (in present value terms) the client earns as a result. Although an ROI measure is straightforward to calculate given its components, credibly estimating program benefits and costs from available data can be difficult (King & O’Shea, 2003; Clapp et al., 2019). In this chapter, we review the empirical literature on VR program ROI. To do so, we first provide an overview of the basic conceptual issues involved in estimating VR program benefits and costs and, ultimately, the ROI of VR programs. Our aim is to highlight some of the key issues in ROI evaluations and how the approaches used in the VR literature have evolved over time, not to provide an exhaustive how-to guide. McGuire-Kuletz and Tomlinson (2015) and articles in the special issue introduced by Schmidt et al. (2019b) provide a more detailed guide to ROI analysis of VR programs.