​Summary: Studies of unmet mental health service needs have typically focused on populations requiring intensive services, such as individuals with serious psychological distress (SPD). Such efforts are critical, as these are often individuals with severe mental health challenges. At the same time, that focus inadvertently misses the vision behind Prevention and Early Intervention (PEI) efforts, mandated in Proposition 63, to intervene early and prevent mental health problems from becoming more severe and disabling. In addition to examining the unmet mental health service needs for adults with SPD who are eligible (adults who were uninsured or who were covered by Medi-Cal or other public insurance programs in the past year) for services through the Mental Health Services Act (MHSA), this policy brief presents the first analysis that identifies and examines the unmet service needs among adults who have moderate psychological distress (MPD) — a group that may benefit from MHSA’s PEI services.