Measures of socioeconomic status (SES) are widely used in educational research and policy applications in no small part because of a deeply rooted belief of the importance of SES. This paper argues that the usefulness of common SES measures can be undermined by (a) an atheoretical approach to conceptualizing SES and selecting measures, which creates uncertainty about what SES represents; (b) modest correlations between SES measures and outcome variables that limit the effectiveness of SES as a control variable in statistical analyses; and (c) the continued use of the profoundly flawed eligibility for a free/reduced-price lunch variable. These factors can produce biased inferences and speak to an important gap between the perceived impact of SES in educational settings and the usefulness of common SES measures and also can provide a prescription for change that promotes a deeper understanding and more effective use of SES in educational research and policy.