Objective: The obesity epidemic is a public health concern, warranting further research into pharmacological treatments for weight management (WM) as an adjunct to lifestyle interventions. The Semaglutide Treatment Effect in People with obesity (STEP) program aims to investigate the effect of semaglutide versus placebo on weight loss, safety, and tolerability in adults with obesity or overweight. Methods: Across five phase 3 trials (NCT03548935, WM; NCT03552757, WM in type 2 diabetes; NCT03611582, WM with intensive behavioral therapy; NCT03548987, sustained WM; and NCT03693430, long-term WM), ~5,000 participants are being randomly assigned to receive semaglutide 2.4 mg once weekly subcutaneously versus placebo. Results will be available in 2020/2021. For all trials, the primary end point is change from baseline to end of treatment in body weight. Results: Participants have a mean age of 46.2 to 55.3 years, are mostly female (mean: 74.1%-81.0%), and have a mean BMI of 35.7 to 38.5 kg/m2 and a mean waist circumference of 113.0 to 115.7 cm. Conclusions: The STEP program evaluates the efficacy and safety of semaglutide 2.4 mg subcutaneously once weekly in a broad population. The trials will provide insights on WM in people with obesity with and without type 2 diabetes and on long-term follow-up.