The ability to trace new and changed requirements to their impacted components provides critical support for managing change in an evolving software system. Unfortunately numerous studies have shown the difficulties of maintaining links using traditional traceability methods. Information retrieval techniques can be used to dynamically generate traces and alleviate the need to maintain explicit links, however prior work in this area has focused primarily on establishing intra-requirement links or links between requirements and code. In this paper we compare several retrieval techniques for generating links between requirements, code, and UML models. Tracing to UML elements provides a higher perspective on the proposed change than would be possible if links were generated directly to the code and supports the growing trend towards Model Driven Development. Our experiment returned better results for establishing links to UML artifacts than to code, suggesting the usefulness of establishing links to code via UML artifacts. We conclude the paper by discussing the implications of this approach for managing the evolution of a software system.