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This page presents catalogs of galaxy groups and clusters identified from the SDSS redshift survey. Groups are identified in volume-limited samples of galaxies that go out to different depths and are complete down to different corresponding luminosities. The group-finding algorithm used is friends-of-friends with different linking lengths along the perpendicular and line-of-sight directions (see Huchra & Geller 1982). The friends-of-friends linking lengths are chosen carefully to select galaxy systems that occupy the same dark matter halos in mock galaxy catalogs, which are constructed by populating halos with galaxies in N-body simulations. The mock catalog tests, group-finding algorithm, and resulting group and cluster catalogs are described in detail in the paper Berlind et al. (2006).