During the 2005 survey year, federal courts in the Second Circuit decided a number of important res judicata matters. Several district courts applied the doctrines of claim preclusion and issue preclusion to administrative and arbitral determinations. Several courts also expanded the “actually litigated” requirement for collateral estoppel and liberally applied the doctrine of defensive claim preclusion for counterclaims. Finally, the United States Court of Appeals for the Second Circuit issued seven res judicata decisions. In one, Vargas v. City of New York, the Second Circuit refined the standards for applying the Rooker-Feldman doctrine. This survey article will review some of the Second Circuit\u27s significant res judicata decisions and will critique those giving preclusive effect to administrative and arbitral determinations