Functional analyses (FAs) are a common tool used in the assessment and treatment of severe problem behaviors and often occur in the context of clinical settings with unfamiliar, trained staff. Previous research suggests that inconsistent outcomes can emerge when caregivers with an existing history of seeing their child’s challenging behavior are trained to implement the assessment in place of clinical staff. The purpose of the current study was to expand on existing literature by comparing FA implemented by clinical staff and caregivers in the context of a clinical setting. Results demonstrate that efficient identification of function and differentiated rates of problem behavior given the inclusion of caregivers during assessment may vary based on the child’s existing history of responding with those caregivers. Implications of results for researchers and practitioners are discussed.