IMPORTANCE Enhanced Recovery After Surgery (ERAS) care has been reported to be associated with improvements in outcomes after colorectal surgery compared with traditional care. OBJECTIVE To determine the association between ERAS protocols and outcomes in patients undergoing elective colorectal surgery. DESIGN, SETTING, AND PARTICIPANTS The Postoperative Outcomes Within Enhanced Recovery After Surgery Protocol (POWER) Study is a multicenter, prospective cohort study of 2084 consecutive adults scheduled for elective colorectal surgery who received or did not receive care in a self-declared ERAS center. Patients were recruited from 80 Spanish centers between September 15 and December 15, 2017. All patients included in this analysis had 1 month of follow-up. EXPOSURES Colorectal surgery and perioperative management were the exposures. Twenty-two individual ERAS items were assessed in all patients, regardless of whether they were included in an established ERAS protocol. MAIN OUTCOMES AND MEASURES The primary study outcome was moderate to severe postoperative complications within 30 days after surgery. Secondary outcomes included ERAS adherence, mortality, readmissions, reoperation rates, and hospital length of stay. RESULTS Between September 15 and December 15, 2017, 2084 patients were included in the study. Of these, 1286 individuals (61.7%) were men; mean age was 68 years (interquartile range [IQR], 59-77). A total of 879 patients (42.2%) presented with postoperative complications and 566 patients (27.2%) developed moderate to severe complications. The number of patients with moderate or severe complications was lower in the ERAS group (25.2% vs 30.3%; odds ratio [OR], 0.77; 95% CI, 0.63-0.94; P = .01). The overall rate of adherence to the ERAS protocol was 63.6% (IQR, 54.5%-77.3%), and the rate for patients from hospitals self-declared as ERAS was 72.7% (IQR, 59.1%-81.8%) vs non-ERAS institutions, which was 59.1% (IQR, 50.0%-63.6%; P < .001). Adherence quartiles among patients receiving the highest and lowest ERAS components showed that the patients with the highest adherence rates had fewer moderate to severe complications (OR, 0.34; 95% CI, 0.25-0.46; P < .001), overall complications (OR, 0.33; 95% CI, 0.26-0.43; P < .001), and mortality (OR, 0.27; 95% CI, 0.07-0.97; P = .06) compared with those who had the lowest adherence rates.