Comm. 27 sponsors three special services for the astronomical community: the Information Bulletin On Variable Stars (IBVS). the Archives of Unpublished Observations of Variable Stars, and the General Catalog of Variable Stars. The news from the centers organizing these activities can be found in Section 2. The subsequent sections present a summary of the developments between 1987 and 1990 in the various scientific fields written by selected experts. We are grateful to the authors for their excellent reviews.