We applied two productivity instruments (the Work Productivity Short Inventory and the Work Limitations Questionnaire) to the same employees working at a large telecommunications firm. In this work we note differences in productivity metrics obtained from these instruments and offer reasons for those differences that may be related to their design. Within this sample, average at-work productivity (presenteeism) losses were 4.9% as measured by the WLQ and 6.9% as measured by the WPSI. These translated into losses of approximately $2000 to $2800 per employee per year, respectively. Total productivity losses were usually not associated with demographics or job type but were associated with perceived health status and the existence of particular medical conditions. Both instruments may be useful for employers who want to estimate productivity losses and learn where to focus their energy to help stem those losses.