The International Astronomical Union Colloquium on Stellar Rotation was held at the Ohio State University in Columbus, Ohio, U.S.A. from September 8th through 11 th, 1969. Forty-four scientists from Argentina, Belgium, Canada, England, Finland, East and West Germany, Italy, Israel, Japan, The Netherlands, and the United States attended and participated in the Colloquium. The present volume, which parallels the actual program closely, contains the papers presented at the Colloquium plus most of the discussion following those papers. The Colloquium was sponsored by the International Astronomical Union, the Ohio State University, and the National Science Foundation. It is a pleasure to record my thanks to these organizations and especially to Dr. Geoffrey Keller, Dean of the College of Mathematics and Physical Sciences of the Ohio State University, and to Prof. C. de Jager, Assistant General Secretary of the International Astronomical Un ion, for their kind cooperation. I am also grateful to H. A. Abt, J. Hardorp, R. P. Kraft, Mrs. A. Massevitch, M. Plavec, 1. W. Roxburgh, and E. Schatzman of the Organizing Committee, as well as A. J. Deutsch and G. W. Collins, II, for their help in planning the Colloquium all of them offered valuable suggestions toward organizing the program.

The International Astronomical Union Symposium No. 70 on Be and Shell Stars, the Merrill-McLaughlin Memorial Symposium, was held in Bass River (Cap Cod), Massachusetts, U. S. A. , from September 15th through 18th, 1975. Fifty-three astronomers from Argentina, Belgium, Canada, Czechoslovakia, France, Israel, the United Kingdom, the United States, and the Vatican attended and participated in the Symposium. This volume, which parallels the actual program closely, contains the papers presented at the Symposium plus most of the discussion following the papers. New observational techniques and fresh theoretical ideas have resulted over the past few years in a renewed interest in Be and shell stars. At IAU Symposium No. 51 on Extended Atmospheres and Circumstellar Matter in Spectroscopic Binary Sys tems, the Otto Struve Memorial Symposium, in Parksville, British Columbia, Canada, three years ago, a number of participants expressed the wish to organize a symposium on Be and shell stars. If we wish to identify an official 'Father of IAU Symposium No. 70', it would be Mirek Plavec who, in his capacity as President of IAU Commission 42 (Photometric Double Stars) requested and received the cooperation of Commissions 29 (Stellar Spectra) and 36 (Stellar Atmospheres), suggested an Organizing Committee, and wrote to the IAU General Secretary in 1973 requesting that the IAU Executive Committee approve the proposed confer ence as an IAU Symposium.