A primary concern in the development of large-scale, real-time, complex, computer-intensive systems is ensuring that the system meets the specified requirements. Further, the requirements themselves evolve and undergo many changes during the development process. In such a context, it is essential to maintain traceability of requirements to various outputs to ensure that the System meets the current set of requirements. An empirical study, utilizing focus group and protocol analysis techniques, was conducted with students from the Naval Postgraduate School in a simulated systems development environment. Based on the analysis of data, this study highlights several major issues that need to be considered in the development of a model of traceability. An initial model of traceability as well as recommendations for future research to refine and validate the model are presented.