Mathematics education is one of the most important but least understood subjects of our age. As science and technology move the world from the age of machines to the age of computers, basic education in the language of science, technology and computers takes on increased importance. In both developed and developing nations, more people than ever before are seeking edu cation in mathematics. Yet there are numerous signs that world-wide mathematics education is of very uneven quality, not attuned to the needs of contemporary society: declining scores on standardized examS7 diminishing number of certified mathematics teach erS7 public outcry at failures of the "new math"7 professional concern with problem solving and applications of mathematics7 uncertainty about the relation of computers and calculators to mathematics instruction. It was in this context of rising expectations and mounting problems that over 2000 mathematicians and mathematics teachers from ar. ound the world gathered in August, 1980, at the University of California in Berke ley, California, for the Fourth International Congress of Mathematical Education CIeME IV).