A configurable organizer is described having releasably securable dividers or partitions for defining areas or compartments within the organizer for receiving items therein. The dividers are secured via retainers having retainer portions that are resiliently shiftable to permit insertion or removal of the retainer portions within openings in the organizer and to permit shifting to a natural outwardly biased position for retaining the dividers with the organizer. Support structures may also be provided to retard or prevent tilting or deflecting of the secured dividers. Additionally, the organizer may include a pair of trays having the openings for receiving the retainers and supports, and the trays may be adjustably and selectively moved relative to each other to expand or contract the organizer as desired, such as to conform to interior dimensions of a drawer.