The nature of aggression or hostility is discussed, and the possible relations between hostility in the personalities of husbands and hostility in the personalities of wives are conceptualized under the heads: (a) Similarity in quantity of aggression; (b) Similarity in pattern of aggression; (c) Oppositeness or complementarity in quantity of aggression; (d) Oppositeness or complementarity in pattern of aggression; and (e) Systematic relations between similar or dissimilar (but not necessarily opposite) patterns of aggression. The first four possibilities are explored by imposing a model on questionnaire data obtained from alcoholics and their wives. The fifth possibility, which is the first to be dealt with, is investigated with the aid of a technique which follows the pattern of the data without imposing a model on them.The analysis demonstrates that exclusive reliance on correlational methods, however complex, may obscure the essential features of a psychological situation. It also shows how the special characteristics of temperamental qualities may be accommodated by the construction of an appropriate model.