Systems and methods are provided for utilizing stringer end caps. One embodiment is a method of forming a stringer. The method includes laying up a stringer preform comprising fiber-reinforced material, placing the stringer preform onto a skin panel preform, bonding an end cap to the stringer preform and the skin panel preform, and co-curing the stringer preform and the skin panel preform while the end cap is bonded to the stringer preform and the skin panel preform, resulting in a composite part that includes the end cap.