In the past, commercial airplane manufacturers have used analytical techniques and nonstructured pilot opinion for workload assessment. Analytic techniques are of particular value to the aircraft manufacturer since they offer both the potential for identifying and correcting workload problems early in the design phase when the cost of change is relatively low and a tool that can provide data for certification. One disadvantage to the available analytic techniques is their lack of fidelity in assessing mental effort. With the current shift of flight deck design placing more mental demands on the flightcrew, workload assessment has taken on a new challenge. The addition of formalized subjective measures to traditional objective analyses can provide information that validates the analytic- and simulation-based estimates of physical workload and enhances estimates of mental workload.Currently, The Boeing Company and Douglas Aircraft Company are jointly working a USAF/FAA workload contract to provide guidelines for selecting workload measures that are valid, reliable, and applicable for aircraft certification. These guidelines will provide a flexible basis for selecting workload measures in future years as flight deck requirements change and will enable the FAA to evaluate workload measurement plans for crew size substantiation and workload acceptability during aircraft certification efforts.Some of the specific topics that will be discussed in this paper include: (a) application of analytic techniques of workload assessment to design and certification; (b) historic application of structured subjective measurement techniques; (c) exploration of new techniques with potential application to design and certification; (d) validity and reliability considerations for workload measurement; (e) practicality and applicability considerations in the flight deck environment.