Methods and systems for optimizing item assortments are disclosed. One method includes receiving a request for an optimized assortment. Data relating to items within a selected initial item assortment and item universe is accessed. Constraints are applied to the items in the assortment to arrive at an optimized item assortment. Constraints include goals for optimization, lock in and lock out rules, and item attribute rules. The method may be performed by a system including one or more computing devices communicating via a network with one or more data storage devices.