The I. A. U. Colloquium No. 29 was held in Budapest, September 1-5, 1975. The subject of the colloquium was: "Multiple Periodic Variable Stars". The colloquium was organized by the Scientific Organizing Committee consisting of W. S. Fitch (Chairman), M. W. Feast, B. V. Kukarkin, P. Ledoux, J. Smak, R. S. Stobie, B. Szeidl, B. Warner and S. C. Wolff. The local organization was placed in the hands of a Committee consisting of the staff of the Konkoly Observatory: B. Szeidl (Chairman), K. Barlai, M. Ill, S. Kany6 and L. Szabados. The colloquium was attended by about 90 scientists representing Australia, Austria, Belgium, Bulgaria, Canada, Czechoslovakia, Denmark, France, F. R. G. , G. D. R. , Greece, Hungary, India, Ireland, Italy, Japan, The Netherlands, New Zealand, Poland, Roumania, South Africa, United Kingdom, U. S. A. and U. S. S. R. Eight sessions were held, viz. 1. . p Canis Majoris Stars. Chairman: W. Wenzel 2. Magnetic and Ap Variables. Chairman: S. C. Wolff 3. Miras and Red Variables. Chairman: P. R. Wood 4. Cepheids. Chairman: R. S. Stobie 5. RR Lyrae Stars. Chairman: B. Szeidl 6. RRs and {) Scuti Stars. Chairman: W. S. Fitch 7. White Dwarfs and Novae. Chairman: B. Warner 8. Close Binaries and X-Ray Sources. Chairman: E. H. Geyer At the beginning of the first session a welcome was presented by Professor G.

Inhalt
Invited Papers.- 1. V. P. Tsessevich: On Double Periodicity in the Light Variation of Variable Stars.- 2. J. R. Lesh and M. L. Aizenman: Observational Aspects of Multiperiodicity in the ? Canis Majoris Stars.- 3. S. Kato: On Excitation Mechanisms of Pulsation in ? Cephei Stars.- 4. S. C. Wolff: The Magnetic Variable Stars.- 5. P. R. Wood: Red Variables.- 6. R. S. Stobie: Cepheids.- 7. A. N. Cox and J. P. Cox: Cepheid Pulsation Theory and Multiperiodic Cepheid Variables.- 8. B. Szeidl: Multiple Periodic RR Lyrae Stars: Observational Review.- 9. R. F. Stellingwerf: Theory of Multiperiodic RR Lyrae Stars.- 10. W. S. Fitch: Multiperiodicity in RRs and ? Scuti Stars: an Observational View.- 11. J. O. Petersen: ? Scuti and RRs Type Variables: Theoretical Aspects.- 12. A. Baglin: Rotation Mixing and Variability in A Stars.- 13. B. Warner: Multiple Periodicities in Cataclysmic Variable and White Dwarf Stars.- 14. H. M. Van Horn: Non-Radial Oscillations of Degenerate Dwarfs: a Theoretical Review.- 15. D. S. Hall: The RS CVn Binaries and Binaries with Similar Properties.