Argues that exploration is a constrained behavior category relative to play and provides an economic illustration of behavioral elements during exploration and play. (MP)

Examines the capability and motivation of 18- and 24-month-old infants to share, help, comfort, and cooperate with their older siblings; the frequency of such prosocial behavior by both siblings; and the children's response to sibling distress. The relationship between prosocial and conflict behavior was also studied. (HOD)