Nonstandard Applications of Computer Algebra at ACA'2009 to be held June 25-28, 2009 at ETS, Montreal, Quebec, Canada Organizers: Eugenio Roanes-Lozano Michael Wester Stanly Steinberg Overview: In many of the ACA conferences from 1996 onwards, we have chaired a session devoted to ``Nonstandard Applications of Computer Algebra''. The session traditionally collects contributions that, while using Computer Algebra techniques and/or Computer Algebra Systems, can not be easily allocated in the ``standard'' sessions. Examples of topics treated in papers presented in previous editions of the conference are: Verification and Development of Expert Systems (using algebraic techniques), Railway Traffic Control, Artificial Intelligence, Thermodynamics, Molecular Dynamics, Statistics, Electrical Networks, Logic, Robotics, Sociology ... A special volume with selected papers from the 2008 and 2009 Nonstandard sessions will be published in Mathematics and Computers in Simulation.