The aim of this study was to compare the structural characteristics of the family system (family power structure) in families with young adults and in families with adolescents. The study covered both the perceived and the desired power structure in the family, and its concurrence among family members (their own perceptions of power vs. the amount of power ascribed to other family members). Two groups of families were examined using self-report questionnaires: in 1997 - 124 families living in Warsaw with at least one child in a specified age range (19-25) and in 1999 - 207 families with at least one child aged 14-18. All family members were asked to fill out questionnaires at the same time during a session held at their home. The findings of the study indicate a clear power structure in the family. All family members (in both groups) perceived the family power structure in a similar way. The least amount of power was ascribed to the child, somewhat more power to the father, and the most to the mother. In the desired hierarchy of power, more power was ascribed to parents but at the same time all the family members would expect the child to have more power. In families with young adults all the family members were in agreement in their rating of power distribution in the family. In families with adolescents, a discrepancy between fathers and children was found.