False negative functional analysis (FA) results may be less likely when caregivers serve as therapists, as problem behavior may be more likely to occur in the presence of a caregiver than with a novel therapist. This case study both replicated and extended prior research on this topic. It provides an example of FA results differing between a caregiver and novel therapist and also showed that FA results may differ across caregivers when they serve as therapists. Copyright © 2012 John Wiley & Sons, Ltd.