The purpose of this study was to evaluate the efficacy of the Home Instruction for Parents of Preschool Youngsters program when implemented within Head Start programs by measuring children's language proficiency scores. Participants were kindergarteners concurrently enrolled in both a Head Start program and the Home Instruction for Parents of Preschool Youngsters program along with a comparison group of kindergarteners only enrolled in a Head Start program. According to the results of the chi-square analysis, all of the children who participated in the "Head Start and HIPPY" group scored "developed" on all sections of Texas Primary Reading Inventory or its Spanish language equivalent, El Inventario de Lectura en Espanol de Tejas. However, only about 33 percent of children in the "Head Start Only" group demonstrated "developed" remarks. The remainder of the "Head Start Only" group (67%) scored "needs intervention" on the Texas Primary Reading Inventory/El Inventario de Lectura en Espanol de Tejas. Children who participated in both Home Instruction for Parents of Preschool Youngsters and attended a Head Start Center showed statistically higher scores in language proficiency ([chi-squared](1, N = 22) = 4.07, p = .04) than children who only attended Head Start. (author abstract)