A reusable beverage container that includes a vessel having an upper end defining an upper opening and that is configured to store a beverage. The reusable beverage container further includes a cap that is removably securable to the upper end of the vessel, and the cap is configured to receive and completely enclose a beverage-ingredient cartridge. The cap of the reusable beverage container includes a lower shell defining a lower opening, an upper shell removably securable to the lower shell, and a cartridge opener extending from the lower shell.