In an attempt to document a broader spectrum of the benefits of their pharmaceutical products, drug companies increasingly seek to include productivity claims in their promotional campaigns. We describe the existing regulatory framework of the Food and Drug Administration (FDA) for considering productivity claims, distinguishing between the traditional “substantial evidence” standard and the “competent and reliable scientific evidence” standard. But the notion of competent and reliable scientific evidence may itself be problematic, even when it is the appropriate regulatory standard, because there exists no consistent measurement approach across diseases, workplaces, jobs, and worker capabilities that is widely accepted in this emerging area of health outcomes research. We examine the various measurement approaches that have been used to quantify the impact of illness and its treatment on workplace productivity, and we describe some of the shortcomings associated with each alternative. This discussion highlights the possible difficulties faced by the FDA in reviewing productivity-based promotional claims. Finally, we suggest possible strategies for furthering this field of investigation.