U.S. safety net programs provide critical support to Americans with low income. This cohort study examined patterns of safety net program take-up over time and associations with sociodemographics and health. Surveys among California households with low income (N=380) conducted in 2020-2021 and 2023 captured take-up of federal assistance programs (Medicaid; Supplemental Nutrition Assistance Program [SNAP]; Special Supplemental Nutrition Program for Women, Infants, and Children; Earned Income Tax Credit; Child Tax Credit) in 2019 and 2021 and health in 2023. Latent transition analysis identified patterns and temporal shifts in program take-up among those eligible. Multivariable regressions examined associations of patterns with sociodemographics and mental and overall health. Analyses were completed in 2024. Three take-up patterns emerged: high take-up of “all programs,” “low SNAP,” and “low tax programs.” Most in “all programs” and “low SNAP” patterns in 2019 remained in 2021. Most starting in “low tax programs” transitioned to “all programs” by 2021. Higher income was associated with lower relative risk of “low tax programs” (RRR=0.37, 95% CI=0.28, 0.49). Hispanic ethnicity was associated with higher relative risk of “low SNAP” (RRR=3.73, 95% CI=1.50, 9.23). Having more children and depressive and anxiety symptoms were associated with higher relative risk of being in “all programs” at both timepoints. No associations were found with overall health. Proportion of respondents with high take-up of all programs increased over the study period, perhaps due to pandemic-era policy changes. Take-up patterns showed associations with mental health, and key differences among sociodemographic subgroups suggest targeted interventions may improve participation.