The authors use the largest available complete redshift sample of rich clusters of galaxies (104 richness R ≥ 1 Abell clusters with distance class D ≤ 4) to construct a three-dimensional catalog of superclusters, complete to z ⪉ 0.08. The criterion of membership in the catalog is quantitative: the density enhancement of clusters over the mean density. The supercluster catalog is presented for various values of the density enhancement parameter. The dependence of the identified sample of superclusters on the overdensity is studied, and the sensitivity of the identified superclusters to various quantities and selection procedures is investigated. The validity of the identification procedure is established by comparisons with random catalogs. A larger sample of 175 R ≥ 0, D ≤ 4 clusters with measured redshifts is also analyzed for supercluster membership.