Although many studies of family constellations exist, only recently have investigators begun to examine the qualities of sibling relationships. The purpose of the present investigation was to develop a systematic framework for describing and assessing such relationship qualities. In the first study, upper elementary school children were interviewed about their perceptions of the qualities of their sibling relationships. These interviews yielded a list of 15 salient qualities. In the second study, a self-report questionnaire that assessed their perceptions of these qualities was administered to a sample of 198 fifth- and sixth-grade children. A principal components analysis yielded 4 underlying factors: (a) Warmth/Closeness, (b) Relative Status/Power, (c) Conflict, and (d) Rivalry. Relative Status/Power was found to be strongly related to the relative ages of the child and sibling. The other 3 factors were also related to various family constellation variables, but these relations were modest in size. Because family constellation variables and the qualities of sibling relationships are not isomorphic with one another, it is important to study relationship qualities directly, rather than simply examining family constellation variables. Some of the determinants of such qualities are discussed.