An archival study was conducted to document (a) types of challenging behavior, and (b) functional assessment outcomes, for a sample of persons with developmental disabilities who were referred to community-practicing behavior analysts for assessment and treatment of challenging behavior. Functional assessment reports, prepared by 17 behavior analysts, were obtained on 174 individuals who presented with total of 536 challenging behaviors that were assessed separately. The most frequent topographical class of behavior was physical aggression, followed by verbal aggression, noncompliance, property destruction, inappropriate verbal and social behavior, and self-injury. Functional assessment yielded a single hypothesized function for 53.2% of all behaviors, but multiple functions for 41.0%. Attention was the most commonly hypothesized function for most topographies of behavior. This finding may be attributable to sample characteristics, or to the use of informant-based functional assessment methods for a majority of sample cases. (Contains 5 tables and 1 figure.)