Michael Klein is a pioneer and leader in the use of computational methods to elucidate the structure and dynamics of condensed matter. He has advanced the frontiers of condensed phase molecular simulations over a broad front. In so doing, his research has influenced the interpretation of experiments on the behaviour of disordered crystals, hydrogen-bonded liquids, conducting fluids, supercooled liquids, self-assembled monolayers and lipid bilayers. Michael’s contributions to the methodology of molecular simulations have been very important for the development of this branch of science.