MRST 2001, the 23rd of a series of meetings in theoretical high energy physics that normally rotate between McGill University, The University of Toronto, The University of Rochester, and Syracuse University, honors the memory of Roger Migneron, a frequent participant in past MRST meetings and a strong contributor to elementary particle physics in Canada. Two special sessions present exciting advances in theoretical high energy physics by several outstanding physicists. Topics include: gravity/geometry; B-physics; quarks, gluons, and mesons; field theory; as well as branes, strings, and things.