The Workshop on "Evolutionary Tinkering in Gene Expression" which was held at the end of August 1988. was planned to celebrate 20 successful Advanced Study Institutes (A. S. I.) in Molecular and Cell Biology. The first Institute was held in 1966 on the Island of Spetsai. after a N. A. T. O. suggestion and was entirely financed by N. A. T. O. The success was immediately so great that the Institute grew very rapidly and in the following years. N. A. T. O .• E. M. B. O. (since 1972) and F. E. B. S. (since 1981) co-sponsored it. Since the start of the AS!. the U. S. National Science Foundation has granted travel money for a limited number of American participants each year. In addition. the course was supported by minor industrial subsidies of varying amounts which enabled the organizers to improve some of the local facilities particularly with respect to the lecture hall. In particular. Boehringer Mannheim has contributed since 1966. Furthermore. the Greek Ministry of Science and Culture has provided support at least for a social event during each ASI.