CompMod 2011, Proceedings of the third international workshop on Computational Models for Cell Processes Aachen, Germany, September 10, 2011, EPTCS 67 Ion Petre and Erik de Vink (eds) This volume contains the final versions of the papers presented at the 3rd International Workshop on Computational Models for Cell Processes (CompMod 2011). The workshop took place on September 10, 2011 at the University of Aachen, Germany, in conjunction with CONCUR 2011. The first edition of the workshop (2008) took place in Turku, Finland, in conjunction with Formal Methods 2008 and the second edition (2009) took place in Eindhoven, the Netherlands, as well in conjunction with Formal Methods 2009. The goal of the CompMod workshop series is to bring together researchers in Computer Science (especially in Formal Methods) and Mathematics (both discrete and continuous), interested in the opportunities and the challenges of Systems Biology.