The availability of a comprehensive software infrastructure is essential for the success a parallel architecture. In order to allow for the greatest possible flexibility, an infrastructure has to be designed in an integrated, easy-to-use manner and with the support of multiple programming paradigms and models to address a wide base of codes. SMiLE provides such an infrastructure for SCI (Scalable Coherent Interface) based clusters. It includes support for both a large range of message passing libraries as well as for almost arbitrary shared memory programming models. In addition, SMiLE also contains initial work on appropriate tool sets for performance optimizations. The complete infrastructure is implemented in way that is as closely relate d to the underlying hardware and is therefore capable of exploiting the benefits of the underlying network fabric and offering them to the user without significant overheads.