Gynecomastia is frequently encountered in the primary care setting. During adolescence, male breast enlargement is most often benign and rarely represents a pathologic mechanism. Careful attention should be paid to both the breast and testicular examination. A detailed history should include an inquiry regarding the use of illicit substances, anabolic-androgenic steroids, herbal products, and medications. The impact of gynecomastia on the adolescent's mental health should be assessed. A workup for pathologic causes is rarely required. Reassurance remains the standard of care for physiologic gynecomastia.