Project Know-How, a small intensive early childhood intervention program, stresses family involvement in attempting to maximize the development of children. Three main components are involved: a preschool program, a mothers' program, and a fathers' program. Project goals are addressed through a three-fold intervention plan involving cooperative counseling, human relations training, and educational and occupational training. This report, part of a 12-year longitudinal follow-up study of the project, addresses questions relating to the effects of social class differences and early intervention on family interaction. During semistructured home interviews, characteristics of communication between mothers and children were analyzed from mothers' and children's taped responses to hypothetical childrearing problems. Results indicated that a control group of middle-SES mother-child dyads and an experimental group of low-SES dyads were more active and less punitive than a control group of low-SES dyads. Experimental dyads were found to agree with each other in the discussion of hypothetical situations more often than those in the two control groups. Middle-SES dyads interrupted more frequently during discussion than those in both experimental and control low-SES groups. Results were considered in the context of other research on family environment and the long term effects of early intervention on family interaction characteristics. (Author/AS)