Examination of responding under various schedule arrangements is a core component of many analyses of operant behavior. Much of the pioneering work in applied behavior analysis was bred from laboratory research involving the exposure of nonhuman subjects to a variety of schedule arrangements. Hodos (1961) described a schedule arrangement in which the requirement to access reinforcement increased on a trial-by-trial basis within the course of a single session. That is, the subject would initially emit a predetermined number of responses before reinforcement delivery (e.g., 20 responses). Following reinforcer delivery, the subsequent response requirement would increase by some increment (e.g., another 10 responses; referred to as a step size) such that in the next trial the subject would be required to complete more responses than in previous trials (e.g., 30 responses before reinforcer delivery, 40 responses before reinforcer delivery). Within-session changes in response requirements in this pattern constitute a progressive-ratio (PR) schedule of reinforcement. The primary clinical application of PR schedules involves assessment and quantification of differential reinforcer efficacy, which has sometimes been referred to as reinforcer potency (i.e., the ability of a reinforcer to maintain behavior). There are several methodological details to be considered when developing PR schedules for use in applied settings. Such factors include determining an appropriate algorithm for the progression of schedule requirements (e.g., increasing additively or geometrically), session-termination criteria (e.g., after cessation of responding for a period of time or after a total amount of time has elapsed), the type of target response to use (e.g., a relatively simple or a more complex operant), and the amount of reinforcement delivered throughout the analysis. Each of these variables has been inconsistently manipulated across the existing applied studies.