We derive the effective superpotential for an (Eta) = 1 SU(N(sub c)) gauge theory with one massless adjoint field and N(sub f) massless fundamental flavors and cubic tree-level superpotential for the adjoint field. This is a generalization of the Affleck-Dine-Seiberg superpotential to gauge theories with one massless adjoint matter field. Using Kutasov's generalization of Seiberg duality, we then find the effective superpotential for a related theory with massive fundamental flavors.