BACKGROUND: There is a growing awareness that patients should be more active and effective managers of their health and health care. Recent studies have found patient activation-or having the knowledge, skills, and confidence to manage one's health, to be related to health-related outcomes. These studies have often relied on self-reported outcomes and often have used small samples. OBJECTIVE: To examine the degree to which patient activation is related to a broad range of patient health and utilization outcomes in a large, insured population. DESIGN: Cross-sectional study of patients at Fairview Health Services in Minnesota. Data on patient activation and patient outcomes were derived from the electronic health record, abstracted in December 2010. PATIENTS: A total of 25,047 adult patients were included in the analysis. They all had a primary care visit in the prior six months and completed the patient activation measure as part of an office visit. MAIN MEASURES: The key independent measure was the Patient Activation Measure. We examined 13 patient outcomes across four areas: prevention, unhealthy behaviors, clinical indicators, and costly utilization. RESULTS: In multivariate models, patient activation was related to 12 of 13 patient outcomes in the expected direction. For every additional 10 points in patient activation, the predicted probability of having an ED visit, being obese, or smoking was one percentage point lower. The likelihood of having a breast cancer screen or clinical indicators in the normal range (A1c, HDL, and triglycerides) was one percentage point higher. CONCLUSIONS: This cross sectional study finds that patient activation is strongly related to a broad range of health-related outcomes, which suggests improving activation has great potential. Future work should examine the effectiveness of interventions to support patient activation.KEY WORDS: patient activation; patient engagement; health care quality.