In this thesis we present our work in designing and implementing a Natural Language Processor for querying Cindi, the Concordia Virtual Library System. The Natural Language Processor, named NLPQC, semantically parses natural language questions and builds corresponding SQL queries for the database. This makes the NLPQC system a Natural Language interface to relational databases. Our contribution to the field of the Natural Language interfaces is done through the reuse of WordNet and of the Link Parser, which are two proven tools from the Open Source domain, and through the introduction of a pre-processor that generates rules and templates for the semantic parsing. The NLPQC system is designed to be platform independent and can accept any database schema.