This study examined the association between index hospitalization characteristics and the risk of all-cause 30-day readmission among high-risk Medicaid beneficiaries using multilevel analyses. A retrospective cohort with a baseline and a follow-up period was used. The study population consisted of Medicaid beneficiaries (21-64 years old) with selected chronic conditions, continuous fee-for-service enrollment through the observation period, and at least 1 inpatient encounter during the follow-up period (N = 15,806). The outcome of 30-day readmission was measured using inpatient admissions within 30-days from the discharge date of the first observed hospitalization. Key independent variables included length of stay, reason for admission, and month of index hospitalization (seasonality). Multilevel logistic regression that accounted for beneficiaries nested within counties was used to examine this association, after controlling for patient-level and county-level characteristics. In this study population, 16.7% had all-cause 30-day readmissions. Adults with greater lengths of stay during the index hospitalization were more likely to have 30-day readmissions (adjusted odds ratio [AOR]: 1.03, 95% confidence interval [CI]: 1.02-1.04). Adults who were hospitalized for cardiovascular conditions (AOR: 1.20, 95% CI: 1.08-1.33), diabetes (AOR: 1.23, 95% CI: 1.10-1.39), cancer (AOR: 1.55, 95% CI: 1.26-1.90), and mental health conditions (AOR: 2.17, 95% CI: 1.98-2.38) were more likely to have 30-day readmissions compared to those without these conditions.