This study examined the family system differences between 40 volunteer natural-father and stepfather families. Family triads consisting of the husband, the wife, and a child whose age ranged from 12 to 15 years were studied. Four instruments were used: (a) the Family Concept Q-Sort; (b) a Semantic Differential; (c) a demographic questionnaire; and (d) an interaction-reaction questionnaire. Analyses of variance on the data obtained from the Q-sorts and the Semantic Differentials indicated that stepfather family systems are different from natural-father family systems along several salient dimensions including psychological adjustment, satisfaction with family, reciprocal understanding, and perceived goodness and potency. It was concluded that the differences between the family systems in terms of their interpersonal relations and perceptions affect the entire stepparent family system and its ability to function adequately.