Strong evidence exists for the efficacy of behavior analytic approaches with children on the autism
spectrum (Carr & Firth, 2005; Weiss 2001, 2005). Many early childhood intervention studies report outcomes based
on pre-school populations (Smith, 1999; Casto & Mastropieri, 1986) while outcome studies for younger populations
are scarcer. We reviewed one year of instructional outcome data from an early intervention classroom that used
applied behavior analysis in concert with verbal behavior. The population served was two and three year olds with
pervasive developmental disorder (PDD). Special instruction was provided in individual and in group formats using
learn units as the basic unit of instruction. Ninety-five percent of the children in this program progressed to lesser
restrictive environments. A cost benefit analysis showed the relative dollar amounts of the learn unit, instructional
sessions, and objectives met for one year.