Abstract: A mixing cap and method for use thereof, wherein the mixing cap is preferably pre-loaded during time of manufacture with selected dry or liquid ingredients to facilitate subsequent consumer use. The mixing cap comprises an apertured inner tube threadably-engageable to the mouth of a bottle, and an outer housing cooperatively-engaged with the inner tube and slidably-restricted thereover via a ridge and slotted flange arrangement. Preloaded ingredients contained within the outer housing may be introduced or discharged into the bottle by simply depressing the outer housing over the inner tube when the ridge is aligned with the slot, thereby permitting the ingredients to flow through the apertures of the outer housing and inner tube and into the liquid contents of the bottle. The combined ingredients and liquid within the bottle may subsequently be shaken without fear or risk of leakage or spillage.