Analog functional analyses (FAs) are commonly used to assess factors that maintain problem behavior of individuals with intellectual disabilities. These analyses are usually conducted by trained staff in clinic settings. However, recent research suggests that FAs conducted by unfamiliar individuals, such as hospital or clinic staff, may result in inaccurate or at least different outcomes. This finding, though, has not been sufficiently examined with young children (i.e., under 5 years of age), where therapist familiarity likely has more influence. The current study compared the outcomes of FAs conducted by unfamiliar staff with FAs conducted by parents for five children ages 2-5 years. Results demonstrate that FAs conducted by unfamiliar therapists may result in a number of differing outcomes, including no responding from the child, failure to identify a particular behavioral function, and decreased rates of responding. (Contains 5 figures.)