As part of a program in which father-adolescent interactions are videotaped in a search for the determinants of achieving behavior, a sample of 37 father-adolescent pairs were studied as the two worked together while the blindfolded adolescent built a tower of irregularly shaped blocks. Discriminant function treatment of coded analysis of verbal and non-verbal behavior showed significant sex differences in both Israeli subjects and a comparison group of Americans. Two-way ANOVAS carried out with the variables which discriminated fathers' behavior to sons and daughters showed that, on the whole, Israeli fathers were close and collegial with their daughters, distant and uninvolved with their sons. This contrasts with American fathers, who show the reverse. The findings are interpreted in light of current social phenomena in Israel. (Author)