BACKGROUND: Readmission rates are a measure of surgical quality and an object of clinical and regulatory scrutiny. Despite increasing efforts to improve quality and contain cost, 6% to 25% of patients are readmitted after colorectal surgery. OBJECTIVE: The aim of this study is to define the predictors and costs of readmission following colorectal surgery. DESIGN: This is a retrospective cohort study of patients undergoing elective and nonelective colectomy and/or proctectomy in the Healthcare Cost and Utilization Project Florida State Inpatient Database 2007 to 2011. Readmission is defined as inpatient admission within 30 days of discharge. Univariate analyses were performed of sex, age, Elixhauser score, race, insurance type, procedure, indication, readmission diagnosis, cost, and length of stay. Multivariate analysis was performed by logistic regression. Sensitivity analysis of nonemergent admissions was conducted. SETTINGS: This study was conducted in Florida acute-care hospitals. PATIENTS: Patients undergoing colectomy and proctectomy from 2007 to 2011 were included. INTERVENTION(S): There were no interventions. MAIN OUTCOME MEASURE(S): The primary outcomes measured were readmission and the cost of readmission. RESULTS: A total of 93,913 patients underwent colectomy; 14.7% were readmitted within 30 days. From 2007 to 2011, readmission rates remained stable (14.6%-14.2%, trend p = 0.1585). After multivariate adjustment, patient factors associated with readmission included nonwhite race, age <65, and a diagnosis code other than neoplasm or diverticular disease (p < 0.0001). Patients with Medicare or Medicaid were more likely to be readmitted than those with private insurance (p < 0.0001). Patients with longer index admissions, those with stomas, and those undergoing all procedures other than sigmoid or transverse colectomy were more likely to be readmitted (p < 0.0001). High-volume hospitals had higher rates of readmission (p < 0.0001). The most common reason for readmission was infection (32.9%). Median cost of readmission care was $7030 (intraquartile range, $4220-$13,247). Fistulas caused the most costly readmissions ($15,174; intraquartile range, $6725-$26,660). LIMITATIONS: Administrative data and retrospective design were limitations of this study. CONCLUSIONS: Readmissions rates after colorectal surgery remain common and costly. Nonprivate insurance, IBD, and high hospital volume are significantly associated with readmission.