Abstract. Residuated frames provide relational semantics for substructural logics and are a natural generalization of Kripke frames in intuitionistic and modal logic, and of phase spaces in linear logic. We explore the connection between Gentzen systems and residuated frames and illustrate how frames provide a uniform treatment for semantic proofs of cut-elimination, the finite model property and the finite embeddability property. We use our results to prove the decidability of the equational and/or universal theory of several varieties of residuated lattice-ordered groupoids, including the variety of involutive FL-algebras.Substructural logics and their algebraic formulation as varieties of residuated lattices and FL-algebras provide a general framework for a wide range of logical and algebraic systems, such as Classical propositional logic ↔ Boolean algebras Intuitionistic logic ↔ Heyting algebras Lukasiewicz logic ↔ MV-algebras Abelian logic ↔ abelian lattice-ordered groups Basic fuzzy logic ↔ BL-algebras Monoidal t-norm logic ↔ MTL-algebras Intuitionistic linear logic ↔ ILL-algebras Full Lambek calculus ↔ FL-algebras as well as lattice-ordered groups, symmetric relation algebras and many other systems.In this paper we introduce residuated frames and show that they provide relational semantics for substructural logics and representations for residuated structures. Our approach is driven by the applications of the theory. As is the case with Kripke frames for modal logics, residuated frames provide a valuable tool for solving both algebraic and logical problems. Moreover we show that there is a direct link between Gentzen-style sequent calculi and our residuated frames, which gives insight into the connection between a cut-free proof system and the finite embeddability property for the corresponding variety of algebras.We begin with an overview of residuated structures and certain types of closure operators called nuclei. This leads to the definition of residuated frames (Section 3) and Gentzen frames (Section 4), illustrated by several examples. We then prove a general homomorphism theorem in the setting of Gentzen frames (Thm. 4.2) and Date: August 25, 2008.