Twenty-four infants and their preschool-aged siblings were observed in a laboratory playroom in the presence of their parents. Observations took place when the infants were 12 months old and again 6 months later. (JMB)

Naturalistic observations of 20-month-old infants and their older siblings (1 1/2 or 3 years older) suggested the presence or absence of the mother may be an important variable in interactions between the two. (BJD)

Results suggested that preschool age siblings may facilitate mastery of the object environment by infants. (Author/JMB)

In a second follow-up study of sibling interaction, 24 pairs of same-sex siblings and 24 pairs of mixed-sex siblings were observed in their homes 18 months after the first follow-up and 3 years after the initial observations. The patterning of interaction was similar to that observed earlier. (Author/DR)

Thirty-six pairs of mixed-sex siblings were observed for two 1-hour periods in their homes. The younger siblings averaged 20 months of age and the interval between siblings was either large or small. Results are compared with a previous study of same-sex sibling interaction. (Author/RH)

Subjects were eight first-graders with older siblings, half from 2-child families and half from larger families. The four sex combinations of sibling pairs were equally represented. Half the children were aided on the task by their mother; half were aided by their sibling. Comparisons were made by sex and family size. nAuthor/JH)

Results are interpreted in terms of role theory and sibling rivalry, and have application for school practice. (Author)