Evaluated was the effectiveness of the Portage Home Visit (PHV) Parent Involvement Program in improving the IQ's, and motor, language, adaptive and personal-social developmental skills of 36 multiply handicapped developmentally delayed preschoolers in rural Wisconsin during 36 consecutive weekly sessions. Home trainers provided parents with technical assistance, an instructional model that included a prescriptive precision teaching approach using positive reinforcement, and information on how to record the children's performance in regard to the prescribed activities. Analysis of pre- and post-test data indicated that Ss showed significant gains in IQ, adaptive behavior, language development and personal-social skills, but that the PHV program was not effective in enhancing their motor coordination skills (due perhaps to the severity of Ss' physical deficits). (LH)