We examine the potential of mental health/substance abuse (MH/SA) parity laws to reduce the out-of-pocket spending burden for outpatient treatment at the state level by exploring cross-state variations and their causes, as well as the provisions of MH/SA parity laws. We find modest (yet important) variation in out-of-pocket burden across states overall, but-because prescription medications account for two-thirds of out-of-pocket spending and are generally beyond the scope of recently enacted federal parity laws-evidence suggests that those laws will do little to reduce the observed burden or its variation. Other policy measures, designed to expand and improve health insurance coverage or reduce racial/ethnic disparities, could have a more profound impact.