The results of this paper extend some of the intimate relations that are known to obtain between combinatory logic and certain substructural logics to establish a general characterization theorem that applies to a very broad family of such logics. In particular, I demonstrate that, for every combinator X, if LX is the logic that results by adding the set of types assigned to X (in an appropriate type assignment system, TAS) as axioms to the basic positive relevant logic B•T, then LX is sound and complete with respect to the class of frames in the Routley-Meyer relational semantics for relevant and substructural logics that meet a first-order condition that corresponds in a very direct way to the structure of the combinator X itself.In this paper I explore how the concepts and structures of combinatory logic can be used to define a very broad class of substructural logics, both prooftheoretically and semantically. In particular, I establish a general result that, for every combinator, X, there is a corresponding logic LX defined by adding the set of types assigned to X (by an appropriate type assignment system TAS) as axioms to the logic B+T, or rather its extension B•T, that is the basic positive relevant or substructural logic familiar from the work of Routley and Meyer [17], [18], etc., and moreover this logic LX is characterized by the class of relational frames of the Routley-Meyer semantics for relevant logics that meet a first-order condition that corresponds in a very direct way to the combinator X itself.To demonstrate this result, even to articulate it precisely, requires laying some groundwork about the basic logic B•T and some elementary combinatory logic. Accordingly, in Section 1 below, I describe B•T and the relational semantics that applies to it and all its extensions to be considered later. Then in Section 2, I present some rudiments of combinatory logic, the theory of weak reduction, both untyped and typed. These two sections cover standard material, and are provided chiefly to establish a language for the results to follow and so that this paper will, by and large, be self-contained. Section 3 draws the two frameworks together, discovering in the relational semantics counterparts of the key elements of combinatory logic. This pro-