The results of a comparison of two typologies of sibling relationships in old age are reported. Both analyses rely on the same data collected in individual interviews with adults over the age of 65. The first typology was constructed using constant comparative analysis; the second relied on the grade of membership (GOM) technique. This is the first time GOM has been used to create a taxonomy of human relationships based on psychosocial variables. The two typologies are compared in terms of number of types generated, the characteristics of each type, factors influencing typological construction, and the utility of empirical results. Implications for additional use of the GOM technique to study late-life sibling relations are discussed.