IntroductionAs expanded Medicaid coverage reduces financial barriers to receiving health care among formerly incarcerated adults, more information is needed to understand the factors that predict prompt use of health care after release among insured adults with a history of substance use. This study's aim was to estimate the associations between characteristics suggested by the Andersen behavioral model of health service use and measures of health care use during the immediate reentry period and in the presence of Medicaid coverage. MethodsIn this retrospective cohort study, we linked individual-level data from multiple Wisconsin agencies. The sample included individuals aged 18–64 released from a Wisconsin State Correctional Facility between April 2014 and June 2017 to a community in the state who enrolled in Medicaid within one month of release and had a history of substance use. We grouped predictors of outpatient care into variable domains within the Andersen model: predisposing- individual socio-demographic characteristics; enabling characteristics including area-level socio-economic resources, area-level health care supply, and characteristics of the incarceration and release; and need-based- pre-release health conditions. We used a model selection algorithm to select a subset of variable domains and estimated the association between the variables in these domains and two outcomes: any outpatient visit within 30 days of release from a state correctional facility, and receipt of medication for opioid use disorder within 30 days of release. ResultsThe size and sign of many of the estimated associations differed for our two outcomes. Race was associated with both outcomes, Black individuals being 12.1 p.p. (95 % CI, 8.7–15.4, P < .001) less likely than White individuals to have an outpatient visit within 30 days of release and 1.3 p.p. (95 % CI, 0.48–2.1, P = .002) less likely to receive MOUD within 30 days of release. Chronic pre-release health conditions were positively associated with the likelihood of post-release health care use. ConclusionsConditional on health insurance coverage, meaningful differences in post-incarceration outpatient care use still exist across adults leaving prison with a history of substance use. These findings can help guide the development of care transition interventions including the prioritization of subgroups that may warrant particular attention.