MASS PROGRAM AT PENN STATE ANATOLE KATOK, SVETLANA KATOK, AND SERGE TABACHNIKOV The MASS program—Mathematics Advanced Study Semesters—is an intensive program for undergraduate students recruited every year from around the USA and brought to the Penn State campus for one semester. MASS belongs to a rare breed; we know of two other, some- what similar, mathematical programs for American undergraduates, both based abroad: Budapest Semesters in Mathematics and Mathe- matics in Moscow; the former is in its “teens” (started in 1985) while the latter is just one year old. Mathematics Advanced Study Semesters at Penn State has turned six, and this seems to be a good time to reflect on the MASS community. How it started All three founders of the MASS program (the first two authors of this article and the first MASS director, A. Kouchnirenko) are steeped in the Russian tradition where interested students are exposed to a variety of mathematical endeavors, often of nonstandard kind, at an early age. By their senior undergraduate years such students are already budding professionals. We briefly describe this tradition in Appendix 1. The U.S. educational system is built on completely different principles, and interested young students are routinely encouraged to go fast through the required curriculum. Here a typical mathematically gifted high school student takes courses in local university and often is considered a nerd by his peers. The founders felt that there was a way to combine some of the best features of both traditions within the U.S. academic environment, namely, to gather a group of mathematics majors and to expose them to a substantial amount of interesting and challenging mathematics from the core fields of algebra, geometry and analysis which goes way beyond the usual curriculum. The second author’s first exposure to an intensive program for U.S. undergraduates was at the Mills College Summer Mathematics Insti- tute for mathematically gifted undergraduate women. But why should such a program be all female? Why not to organize a co-educational program along the same lines whose participants would contribute a Date : December 13, 2001. 1