A variety of resources developed for use with the Unified Medical Language System are presented. These resources include the UMLS Knowledge Source Server, the SPECIALIST lexicon, a set of lexical tools that work with the SPECIALIST lexicon, and a variety of other NLP document processing tools. These tools manage lexical variation, tokenize and parse text strings, suggest spelling variants, and provide text-to-concept mapping capabilities. The UMLS Knowledge Source Server is available under a license agreement. The other tools are freely downloadable.