The Operator Workload (OWL) Program is a just-completed, three-year, basic and applied research effort sponsored by the Army Research Institute (ARI). As part of the Army's research thrust into workload, the OWL Program was directed to establish guidance for the assessment of OWL associated with the operation of Army systems. Its intent was to identify and integrate the most relevant of workload research into a set of practicable workload assessment methods for Army developers, and then apply and validate these methods on selected Army systems. Lessons learned from OWL studies of these systems formed the basis for guidance for Army system developers. This paper overviews the objectives, the accomplishments, and the future prospects of the OWL Program.