Preschool children's interactions with friends and older siblings: relationship specificity and joint contributions to problem behavior.

The primary aim of the present study was to examine the extent to which friend and sibling relationship quality jointly contribute to children's behavioral adjustment. Preschool-aged children (N = 52) were observed separately with a friend and an older sibling during a free-play session and a sharing task. Mean comparisons indicated that friendship dyads, on average, engaged in more complex social play and more intense conflict (but only during free play), whereas sibling dyads were characterized by greater asymmetry. Few friend-sibling associations emerged. Friend and sibling relationship quality in the sharing task together accounted for a significant portion of variance in parent-reported aggressive-disruptive behavior, and a Sibling x Friend interaction indicated that greater relationship quality with one partner buffered children from poor behavioral adjustment when relationship quality with the other partner was low or moderate. Implications for preventive intervention efforts are discussed.