In collaboration with the SOC, the SSC is making a major contribution to the development of the XMM Science Analysis Subsystem (SAS). The SAS provides XMM-specific software tools for all XMM science data. It allows the processing of the Observation Data Files (ODF s) sent to the observer through to high-level science products, but does not, in general, aim to provide the high-level analysis tools (e.g., spectral fitting) themselves.