This paper draws from data on 123 languages to examine the semantics of comparative systems in an attempt to define as closely as possible the relationships that exist among three basic types of constructions and among their constituents. It is determined that superlatives mark absolute disparity, that comparatives mark relative disparity, and that superlatives and comparatives are more closely related to each other than to equatives. Analysis of degree marker types reinforces the close relationship between comparatives and superlatives as opposed to equatives. Suppletive paradigms furnish yet another link in the chain of evidence relating comparative and superlative on the one hand and positive and equative on the other. The markedness hierarchy theory, i.e., that the superlative is more marked than the comparative and the latter more than the positive, is further supported by the fact that superlative degree markers may be derived from comparative degree markers but not the converse. Appendixes include: tables of standard and degree markers, of hypotactic marker types, and of formal identity or near-identity of markers. (Author/AM)