One-hundred seventy-three studies that employed functional assessment were evaluated with respect to types of challenging behaviors studied and the functions identified that maintained those behaviors. For most studies, two to three behaviors were targeted. Of the 38 different challenging behaviors identified, self-injurious behavior (SIB) and aggression were by far the most studied. Other commonly studied behaviors were tantrums, stereotypies, property destruction, bizarre/inappropriate speech/vocalizations, and disruptive behaviors. The most commonly identified functions for both SIB and aggressions were attention and escape/demands. The implications of these and other data complied on target behaviors and maintaining variables are discussed. (Contains 1 figure.)