This chapter presents an approach to software development where model-driven development and software reuse facilities are combined in a natural way. It shows how model transformations building a Platform Independent Model (PIM) can be applied directly to the requirements specified in RSL by domain experts. Further development of the software case (PSM, code) is also supported by transformations, which in addition ensure a rich traceability within the software case. Alternatively, the PSM model and code can also be generated directly from requirements in RSL, thus providing fast development of the final code of at least a system prototype in many situations. The reuse support relies on a similarity-based comparison of requirements for software cases. If a similar part is found in an existing software case, a traceability link-based slice of the solution can be merged into the new case. The implementation of the approach is briefly sketched.