This paper is concerned with the question of how to extract lexical knowledge from Machine-Readable Dictionaries (MRDs) within a lexical database which integrates a lexicon development environment. Our long term objective is the creation of a large lexical knowledge base using semiautomatic techniques to recover syntactic and semantic information from MRDs. In doing so, one finds that reliance on a single MRD source induces inadequacies which could be efficiently redressed through access to combined MRD sources. In the general case, the integration of information from distinct MRDs remains a problem hard, perhaps impossible, to solve without the aid of a complete, linguistically motivated database which provides a reference point for comparison. Nevertheless, advances can be made by attempting to correlate dictionaries which are not too dissimilar. In keeping with these observations, we describe a software package for correlating MRDs based on sense merging techniques and show how such a tool can be employed in augmenting a lexical knowledge base built from a conventional MRD with thesaurus information.