Introduces a self-esteem maintenance model and uses it to make predictions about sibling identification, sibling friction, and the closeness of father–son relationships. Two studies were conducted with 513 university students. Consistent with the predictions of the model, identification decreased and friction increased with closeness in age, when S reported that his/her sibling performed better on important dimensions. When S reported that he/she performed better than his/her sibling, the relationship to closeness in age was reversed for identification and severely attenuated for friction. As predicted, the closeness of the relationship between fathers and their eminent scientist sons was a negative function of the similarity in their occupations. Sex effects, the relationships between friction and identification, and the role of threat to self-esteem as a hypothetical variable are discussed. (19 ref) (PsycINFO Database Record (c) 2016 APA, all rights reserved)