A container system for separately storing and mixing two or more substances. The container system is comprised of a main container for holding at least one first substance and a cup for holding at least one second substance, the cup being removably mounted on the neck of the main container such that at least a portion of the cup is suspended within the main container. The cup has an upper portion, a lower portion and one or more arms for connecting the upper and lower portions. Apertures are formed between the upper and lower portions of the cup such that the contents of the cup may mix with the contents of the main container following removal of an inner cap attached to the cup, and agitation of the main container. The cup and neck are sized to provide a void therebetween, thereby also permitting the substances to mix.