Program evaluation is an essential practice for providers of behavior analytic services, as it helps providers understand the extent to which they are achieving their intended mission to the community they serve. A proposed method for conducting such evaluations, is through the use of a consecutive case series design, for which cases are sequentially gathered following the onset of a specific occurrence. Given the sequential nature in which data are collected within a consecutive case series, analytic techniques that adopt a time-series framework may be particularly advantageous. Although such methods are commonly used for program evaluation in medicine and economics, their application within the field of applied behavior analysis is largely absent. To serve as a model for providers undertaking evaluation efforts, I conducted a program evaluation of an outpatient severe behavior clinic, in which I employed quasi-experimental methods using an interrupted time-series analysis.