Description:This book constitutes the refereed proceedings of the 5th International Conference on Machines, Computations, and Universality, MCU 2007, held in Orleans, France, September 10-13, 2007. The 18 revised full papers presented together with 9 invited papers were carefully reviewed and selected. The topics include Turing machines, register machines, word processing, cellular automata, tiling of the plane, neural networks, molecular computations, BSS machines, infinite cellular automata, real machines, and quantum computing.