The authors conducted descriptive and experimental analysis of problem behaviors in the homes of 5 children. The children's parents were actively involved in the descriptive assessment and manipulated potential controlling variables during the experimental analysis. The information obtained from each functional assessment method (e.g., behavioral interview, direct observation assessment, experimental analysis) indicated the same function for each child's problem behavior. Based upon the results of the descriptive analysis, experimental analysis conditions were designed to test specific hypotheses regarding the function of the challenging behavior. Through the brief experimental analysis, we verified the function of the children's problem behaviors in four to six sessions. Interventions involving functional communication training (FCT) were implemented based upon the assessment results for 2 of the children. The effectiveness of FCT for these 2 children validated the functional assessment results. The study employed parents in their natural environment and suggested that functional assessment procedures may be useful and/or practical in natural settings.