IMPORTANCE: Considerable efforts have been undertaken to relate single nutrients to bone health. To this point, results are inconsistent. Suboptimal single nutrient intake does not occur in isolation but rather reflects a poor diet quality. OBJECTIVE: To assess the association between adherence to a diet quality index constructed on the basis of dietary recommendations or existing healthy dietary patterns and fractures in postmenopausal women. DESIGN, SETTING, AND PARTICIPANTS: Post hoc analysis was conducted of longitudinal data from 40 clinical centers throughout the United States included in the Women's Health Initiative (WHI) observational study. Participants in the prospective cohort included 93 676 women who were eligible for the WHI if they were aged 50 to 79 years. Recruitment was conducted from October 1, 1993, to December 31, 1998, with the study ending August 29, 2014. The WHI food frequency questionnaire was used to derive nutrient and food intake at baseline. Diet quality and adherence were assessed by scores on the alternate Mediterranean Diet (aMED), a 9-category measure of adherence to a Mediterranean dietary pattern; the Healthy Eating Index 2010 (HEI-2010), a 100-point measure of 12 food components; the 11-item Alternate Healthy Eating Index 2010 (AHEI-2010); or the 8-component Dietary Approaches to Stop Hypertension (DASH) diet score. MAIN OUTCOMES AND MEASURES: Outcome measures included incident total and hip fractures. Hazard ratios (HRs) by quintiles of dietary index scores were estimated using Cox proportional hazards regression analyses. RESULTS: Of the 93 676 participants, 90 014 were included in the analysis (mean [SD] age, 63.6 [7.4]) years. During a median follow-up time of 15.9 years, there were 2121 cases of hip fractures and 28 718 cases of total fractures. Women scoring in the highest quintile (Q5) of the aMED index had a lower risk for hip fractures (HR, 0.80; 95% CI, 0.66-0.97), with an absolute risk reduction of 0.29% and a number needed to treat of 342 (95% CI, 249-502). No association between the aMED score and total fractures was observed (Q5 HR, 1.01; 95% CI, 0.95-1.07). Higher HEI-2010 or DASH scores tended to be inversely related to hip fracture risk, but the results were nonsignificant (Q5 HR, 0.87; 95% CI, 0.75-1.02; and Q5 HR, 0.89; 95% CI, 0.75-1.06, respectively). The AHEI-2010 score was associated with neither hip nor total fractures. CONCLUSIONS AND RELEVANCE: Higher adherence to a Mediterranean diet is associated with a lower risk for hip fractures. These results support that a healthy dietary pattern may play a role in maintaining bone health in postmenopausal women.