This book constitutes the refereed proceedings of the Third International Workshop on Applied Reconfigurable Computing, ARC 2007, held in Mangaratiba, Brazil, in March 2007.The 27 full papers and 10 short papers presented together with a late-comer contribution from ARC 2006 were thoroughly reviewed and selected from 72 submissions. The papers are organized in topical sections on architectures, mapping techniques and tools, arithmetic, and applications.