We trained parents to conduct functional analyses (n = 25) and functional communication training (n = 23) in home settings over a four-year period with 25 young children who had developmental and behavioural disorders. For 12 of the children, pre-treatment (baseline) probes and post-treatment stimulus condition probes were conducted to assess stimulus generalization of treatment across persons, settings, and tasks. Single-case analyses were conducted to evaluate each child's responding during assessment and treatment. The results were averaged across children to provide an overall summary of the project. Social functions (positive and/or negative reinforcement) were identified via functional analyses for 21 of 25 children (84%). Treatment resulted in pre/post decreases in destructive behaviours averaging 85% across children, with only one child showing no decrease in destructive behaviours. Similar results occurred for total problem behaviour. Mean pre/post decreases occurred across all stimulus conditions (8.38% to .69% for persons, 9.02% to 2.11% for settings, and 10% to 3.47% for tasks). Substantial reductions in training time also occurred for five children who received training on a second task. The procedures were rated as very acceptable by most parents. These results replicate previous findings that functional analysis plus functional communication training is an effective and acceptable procedure. The results extend previous findings by showing substantial stimulus generalization with respect to reductions in total problem behaviour.