Software Process Simulation (SPS) research has increased since 1998 when the frst ProSim Workshop was held. Thispaper aims to reveal how SPS has evolved during the past 10 years based on the preliminary results from the systematic literature review of SPS publications from 1998 to 2007. Trends over the period showed that interest in continuous modelling was decreasing and interest in micro-processes was increasing. Hybrid models were based primarily on system dynamics and discrete event simulation and were all implemented by vertical integration.