Economically disadvantaged individuals with chronic disease have high rates of in-patient (IP) readmission and emergency department (ED) utilization following initial hospitalization. The purpose of this study was to explore the relationships between chronic disease complexity, health system integration (admission to accountable care organization [ACO] hospital), availability of care management interventions (membership in managed care organization [MCO]), and 90-day post-discharge healthcare utilization. We used de-identified Medicaid claims data from two counties in western New York. The study population was 114,295 individuals who met inclusion criteria, of whom 7,179 had index hospital admissions in the first 9 months of 2013. Individuals were assigned to three disease complexity segments based on presence of 12 prevalent conditions. The 30-day inpatient (IP) readmission rates ranged from 6% in the non-chronic segment to 12% in the chronic disease complexity segment and 21% in the organ system failure complexity segment. Rehospitalization rates (both inpatient and emergency department [ED]) were lower for patients in MCOs and ACOs than for those in fee-for-service care. Complexity of chronic disease, initial hospitalization in a facility that was part of an ACO, MCO membership, female gender, and longer length of stay were associated with a significantly longer time to readmission in the first 90 days, that is, fewer readmissions. Our results add to evidence that high-value post-discharge utilization (fewer IP or ED rehospitalizations and early outpatient follow-up) require population-based transitional care strategies that improve continuity between settings and take into account the illness complexity of the Medicaid population. © 2016 Wiley Periodicals, Inc.