Four years ago, in 1975, we met in Cambridge, England for our first IAU Symposium devoted entirely to binary stars. Most of the talks given there were theoretical, and at the end some of us felt that it would be appropriate to organize yet another Symposium soon, this time oriented more towards observations and their immediate interpretation. This is why we have come together here in Toronto. Four years is not a long interval of time, and few disciplines of astronomy repeat their Symposia on such a short time scale. While the need for another Symposium was clear to the binary stars investigators, it is not so obvious to other colleagues. We must therefore be very grateful to the Executive Committee of the International Astronomical Union for their great understanding of our needs. This understanding went far beyond approving and sponsoring this meeting: We have received a substantial financial assistance, which all went to the support of the travel expenses of some of the participants. Many more travel grants were possible thanks to a most generous support by the University of Toronto. I would like to thank both institutions.