Risk of readmission is elevated in patients congestive heart failure (CHF), and clinical decision makers need to better understand risk factors for 30-day readmissions. To identify risk factors for readmission in patients with CHF. We studied all admissions for patients with CHF during 2011 using a statewide discharge data set from Pennsylvania. The primary outcome was readmission to any Pennsylvania hospital within 30 days of discharge. Of 155,146 CHF patients admitted, 35,294 (22.8%) were readmitted within 30 days. Male sex, black race, coverage by Medicare, comorbidities, discharge to a skilled nursing facility or with a home nurse, a longer length of stay (LOS), admission from another facility, and emergent admission (all p < 0.001) were significant risk factors. Comorbidities, sociodemographic factors including male sex, age, black race and Medicare coverage, and prolonged length of stay are associated with increased risk of readmission in patients with CHF.