The purpose is to identify risk factors of functional outcome following proximal humerus open reduction and internal fixation. Patients treated for proximal humerus fractures with open reduction and internal fixation were enrolled in a prospective data registry. Patients were evaluated for function using the Disability of the Arm, Shoulder and Hand score for 12 months and as available beyond 12 months. Univariate analyses were conducted to identify variables associated with functional outcome. Significant variables were included in a multivariate regression predicting functional outcome. Demographics and minimum of 12 month follow-up were available for 129 patients (75%). Multiple regression demonstrated postoperative complication (B=8.515 p=0.045), education level (B=-6.269p<0.0005), age (B=0.241p=0.049) and Charlson Comorbidity Index (B=6.578, p=0.001) were all significant predictors of functional outcome. Orthopaedic surgeons can use education level, comorbidities, age, and postoperative complication information to screen patients for worse outcomes, establish expectations, and guide care.