The main reconstruction techniques for proximal humerus tumors include osteoarticular allografts (OAs), endoprostheses (EPs), or allograft prosthetic composites (APCs). A common complication is infection, and constructs involving the use of allografts are believed to be at a higher risk of infection. Literature comparing infection rates between different modalities of reconstruction is scarce and underpowered. The study purposes were (1) to determine and compare the prevalence of infection in patients who underwent reconstruction of the proximal humerus including OAs, EPs, and APCs; (2) to identify preoperative, perioperative, and postoperative predictors of infection that might be modifiable; and (3) to present our protocol of treatment in patients with superficial and deep infections. We reviewed 150 patients of all ages with proximal humerus tumors treated by an OA, EP, or APC at 2 tertiary institutions. The prevalence of infection for each modality was calculated and compared between groups. We identified potential predictors of infection with stepwise backward multivariate Cox regression analysis. An infection developed in 19 patients (12%): 5 of 45 (11%) in the OA group, 12 of 85 (14%) in the EP group, and 2 of 20 (10%) in the APC group (P = .740). A lower preoperative hemoglobin blood level and low preoperative albumin blood level were independently associated with infection. We found similar infection rates compared with previously reported series. However, we did not identify a higher infection prevalence in constructs using allografts. Patients with a lower preoperative hemoglobin or albumin level are at higher risk of infection and should undergo optimization before surgery.