A 4-month-old boy was brought to the emergency department with a 3-day history of swelling and redness on the right side of the neck. Since birth, he had had a small skin pit in that location. His body temperature was 37.9°C. On physical examination, there was a punctate depression anterior to the sternocleidomastoid muscle that was surrounded by swelling and erythema. Aspiration was performed, and a culture of the fluid grew Staphylococcus lugdunensis and Bacteroides pyogenes. The patient was treated with a 2-week course of amoxicillin–clavulanate. Subsequent magnetic resonance imaging of the neck showed a noncommunicating, saccular structure that extended from the area of the right palatine tonsil to beneath the skin of the lateral neck. A final diagnosis of a second branchial cleft cyst complicated by an infection was made. Second branchial cleft cysts are the most common type of branchial cleft malformations. Skin pits or masses in the lateral neck should arouse suspicion for this condition. The cyst was surgically excised 4 months after the initial presentation. At follow-up 6 months after surgery, the patient’s symptoms had resolved.