In recent years, academic return on investment (A-ROI) has gained growing attention from policy makers as well as education practitioners and stakeholders as a tool to drive how limited financial resources are used to improve student achievement. In this series, we discuss five basic issues around using A-ROI for informing and improving resource use decisions: 1) validity, 2) uncertainty, 3) commensurability, 4) cost, and 5) unit of analysis. This discussion explains how we conceptualize A-ROI as an alternative method to rigorous cost-effectiveness analysis. It also provides a context for how these issues are approached in our A-ROI method and how we suggest results produced through this method should be interpreted and properly used in practice, which will be documented in another report. In this first installment, we focus on the validity of A-ROI as a cost-effectiveness measure.