Food insecurity affects 14% of US homes with children and has been associated with increased mental health problems. Few studies have examined long-term consequences for mental health and the role of social policies. This study examined the association between childhood household food insecurity (HHFI) and young adult psychological distress, and the moderating role of caregiver psychological distress and the Supplemental Nutrition Assistance Program (SNAP) using data from the Panel Study of Income Dynamics (1995-2015). The sample comprised 2782 children ages 0-12 years in 1997. Past-year HHFI was measured using the USDA 18-item questionnaire in 1997, 1999, 2001 and 2003. Young adults' non-specific psychological distress was measured with the Kessler (K6) scale in 2005, 2007, 2009, 2011, 2013 and 2015. Three trajectories of food insecurity were identified: 1) Persistent food security (70.5%); 2) Intermediate/fluctuating food insecurity (24.6%), and; 3) Persistent food insecurity (4.9%). Compared to persistent food security, fluctuating and persistent food insecurity were associated with significantly higher levels of psychological distress. This association was robust to adjusting for socio-demographic factors, caregiver psychological distress, and family access to governmental supports: [Adj. ORs (95% CI's = 1.72 (1.59-1.85) and 2.06 (1.81-2.33)]. Having a caregiver who suffered from psychological distress (1997 and/or 2002) and growing up with persistent food insecurity placed children at greater risk for mental health problems. Access to SNAP attenuated this risk. Early HHFI is associated with psychological distress in young adulthood. Interventions to increase access to SNAP and address caregivers mental health may prevent mental health problems associated with childhood HHFI.