Although functional analysis (FA) remains the standard for identifying the function of problem behavior for students with developmental disabilities, traditional FA procedures are typically costly in terms of time, resources, and perceived risks. Preliminary research suggests that trial-based FA may be a less costly alternative. The purpose of this study was to add to the burgeoning evidence on trial-based FA. Working with students with disabilities, school-based paraprofessionals conducted trial-based FAs for four students with developmental disabilities emitting high-frequency problem behavior. We then conducted brief contingency reversals to assess validity of hypotheses derived from the trial-based FA. Results of the present study add to the small but growing evidence base validating the trial-based FA as a practical and flexible alternative to the standard FA in school settings.