In this study, the outcomes of descriptive, experimental and informant-based methods of functional assessment were compared in four individuals with developmental disabilities who showed problem behaviors. Results indicated that the descriptive and experimental assessments were concordant in only one of the four cases whilst informant-based and experimental assessments were concordant in three of the four cases. The descriptive assessment identified thin schedules of attention in all cases. These results appear to question the usefulness of employing descriptive assessments for problem behaviors either as an adjunct or replacement for experimental assessments, particularly given their time-consuming nature.