The Improved Salad Dressing Preparation and Storage Container is a food preparation device that allows for conveniently measuring, mixing, and dispensing of homemade vinaigrette salad dressing. The device uses two adjacent, adjoined compartments that are volumetrically proportioned to allow for the recommended ratio of oil and vinegar (acid) to be consistently achieved by filling them with oil and vinegar to the same apparent level. The Improved Salad Dressing Preparation and Storage Container may also be configured for commercial sale pre-filled with the oil and vinegar contents, those kept separated by sealing the adjoined compartments using an adapted seal. The pre-filled container may be designed and marketed for secondary use by consumers for use in making their own vinaigrette salad dressing recipes.