Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


This study examined the effects of sibling involvement on preschool developmentally delayed children enrolled in home-based intervention programs. The study was conducted in three parts using quantitative and qualitative methodologies. In Part 1, experimental and control groups were given differential home-based intervention. Siblings of delayed children in the experimental group were included in home-based intervention with the teachers and in practice sessions with the parents. Analysis of covariance of scores on a developmental scale was employed to examine differences in the two groups. Three case studies of children were developed which illustrated the positive benefits and difficulties of including siblings in early intervention. Teachers were interviewed to examine positive and negative aspects of directed sibling involvement. In Part 2, two families (delayed child, sibling, mother, teacher) were observed during home-based sessions. Family A was observed for 15 weeks of pre-intervention which included having the sibling present but not active in the sessions. Family B was observed for 25 weeks which included 15 weeks of pre-intervention and 10 weeks of intervention. Time-series analysis was used to determine if significant differences in behaviors occurred. In Part 3, ethnographic methodology was used to obtain family and life histories of Families A and B. This phase provided contextual information for interpretation of the observations of Part 2. The effectiveness of directed sibling involvement was not demonstrated in the quantitative analyses of the study. No significant differences in performance were obtained between experimental and control groups. Changes of behavior in the observation study were not spontaneous but due to historical events or directly aligned to the strength of teacher direction. The teacher interviews, case studies, and family histories indicated that siblings of similar age were difficult to manage in structured or practice sessions, although it was agreed that siblings were capable of powerful influence upon each other's learning. Older siblings were perceived as more effective teachers than younger siblings. Including fathers in more active roles in early intervention was also seen as desirable. The study indicated the possible importance of directed sibling involvement with delayed children and the need for further investigation.