In bilateral shoulder arthroplasty patients, it is unclear what features are responsible for the timing of their contralateral shoulder arthroplasty. This study hypothesized that patient factors (age, gender, and hand dominance), disease factors (diagnosis and radiographic severity of contralateral shoulder), and surgical factors (type of arthroplasty) impact the timing to contralateral surgery. A retrospective review of 332 patients treated with bilateral anatomic (TSA) or reverse (RSA) shoulder arthroplasty (172 TSA/TSA, 107 RSA/RSA, or 53 TSA/RSA) were divided into groups depending on the interval timing between arthroplasty surgeries: group 1, n = 142 (≤1 year); group 2, n = 62 (1-2 years); and group 3, n = 128 (≥2 years). Preoperative factors were analyzed to determine associations between different time groups, including age, gender, hand dominance, diagnosis, radiographic severity of contralateral shoulder, and type of surgery. Bilateral diagnoses included 211 osteoarthritis (OA), 36 cuff tear arthropathy (CTA), 13 inflammatory arthritis, 12 massive cuff tears without OA, and 4 avascular necrosis. OA patients had their contralateral shoulder arthroplasty sooner than CTA patients (P = .035). OA patients with arthritic changes on contralateral radiographs before the first arthroplasty had their contralateral arthroplasty sooner than those without contralateral radiographs (P < .0001). Patients who had TSA first had their contralateral arthroplasty sooner than patients who had RSA first (P = .037). This study confirmed our hypothesis identifying preoperative variables associated with different time intervals between arthroplasties. The preoperative factors associated with the highest likelihood of having contralateral shoulder arthroplasty within 1 year included OA, radiographic bilateral shoulder disease, and TSA for the first surgery.