This Report in arrangement of the material follows closely that written by Dr. Herbig for the last IAU General Assembly. It consists of four parts, each written by a different author. The first deals with variable stars in general, and was prepared by the President of Commission 27, with the exception of a section on the Theory of Variable Stars, very kindly written at his request by Prof. Kippenhahn. Appendix I on the Spectra of Variable Stars was prepared by Dr M. W. Feast, Chairman of that Committee of Commission 27. Appendix II covers the Variable Stars in Clusters, written by Dr Helen Sawyer-Hogg, Chairman of that Committee. Appendix III is a Report of the Working Group on Flare Stars, prepared by Drs Andrews, Chugainov, Gershberg and Oskanjan. No report has been received from the Working Group for Nomenclature for Magellanic Cloud Variables. About supernovae see the report of the Committee of Commission 28 for Research on Supernovae. On pulsars see the Reports of Commissions 25 and 40. Our thanks are due to all members of the Commission and to other astronomers occupied in variable star research, who have assisted in collecting the material for this report. Great help was a general report on flare stars by the competent Working Group.