Even the best known and most influential comparative outcome studies are not 100% effective in achieving a single best outcome for all of the participants. Lovaas’ (1987) study of the treatment of preschool aged children using intensive ABA intervention achieved a favorable outcome for 47% of the experimental group. Similarly, Sallows and Graupner (2005) reported that 48% of their young participants showed rapid learning with ABA instruction. The changes in preschoolers who made the greatest gains in these studies are heartening, but with half of the children failing to make such major gains we need to identify other strategies that may enhance the learning of the children whose progress was more limited.