Since the pioneering days of the experimental analysis of behavior, free-operant methods have been the hallmark of a behavioral science because they permit investigators to track moment to moment changes in behavior rate. Behavior rate as a dependent variable is more sensitive to momentary changes than statistical analysis, discrete-trial arrangements, and between-subject examinations of aggregate data. In reviewing the gambling literature on slot machine studies, we found that none has focused on free-operant preparations. This lack of free-operant use is likely because of the limitations in designing a practical apparatus to study slot machine gambling through free-operant means. We provide a rationale for free-operant analyses in slot machine gambling as well as proposed methods to bring free-operant preparations to slot machine research. While non-free-operant arrangements have many merits, free-operant preparations will give additional insight into the development of problem gambling while making use of the behavior analyst’s metric of choice: behavior rate.