Input language may have an effect on child development that goes far beyond language development alone. Language is the medium by which children acquire at least a portion of their sex role and social class or group characteristics, world view, and emotional and psychological well-being. Existing theories of psychological development ignore language, attempting to correlate parent behaviors and child outcomes without taking advantage of the substantial research on parent-child linguistic interactions. While developmental psychologists recognize that internalization of parental characteristics through identification is a broad and pervasive aspect of the young child's personality development, it is treated as a magical process in the literature of child development, ignoring language directed at the child as a likely vehicle for transmission of the parents' orientation and value system. Several decades of data on parent-child interaction gathered by linguists can and should be used to illustrate the role that language plays in child development. (MSE)