The classical attachment theory holds to the notion of a monotropic model. Such a model leads to a view of the mother as first and most important figure in an infant's life. A polytropic view of attachment moves us toward a model of simultaneous and multiple attachment figures. In particular, it is argued that peer attachment is a separate but related system. A review of children's peer relationships, including siblings, leads to the consideration of a social network model in which a variety of different people satisfy a variety of different needs of the child.