An improved system and method for the selection and dispensing of reagents onto a target testing medium in an automated laboratory environment. The system utilizes multiple carousels rotatably-mounted upon a central turntable. The position of the central turntable, as well as the rotation of each carousel is controlled by a microprocessor-based control system. Multiple dispensers, each capable of storing and dispensing a particular reagent, are mounted about the circumference of each carousel. This configuration provides much higher reagent density than previously available. The testing medium is positioned at one or more loading stations. The control system directs the central turntable to a position from which a selected one of the carousels can be rotated so as to position a selected dispenser above the testing medium. The selected dispenser is then actuated to release a predetermined reagent onto the testing medium. The system can be configured so that multiple reagents can be dispensed, each from an associated dispenser, onto a single or multiple testing mediums. Each of these actuated dispensers being positioned over the targeted testing medium(s) positioned at one or more loading stations.