The Proceedings of the Sixth Berkeley Symposium on Mathematical Statistics and Probability continues the tradition of this esteemed series, which has been held every five years since 1945. This iteration, spanning multiple sessions from 1970 to 1971, reflects the breadth and evolution of probability theory, statistical analysis, and their applications to emerging scientific challenges. The symposium was structured to cover not only theoretical advances in statistics and probability but also pressing interdisciplinary issues such as molecular evolution, biological health, and environmental pollution, demonstrating the increasingly expansive role of statistical methodologies in scientific inquiry. Comprising over 3,000 pages of research, these proceedings serve as a vital compendium of contemporary thought in probability and statistics. The volumes include contributions from leading mathematicians and scientists worldwide, fostering collaboration across disciplines and nations. Notably, the symposium acknowledges the loss of two intellectual giants, William Feller and Alfred Rényi, whose influence on probability theory remains profound. With rigorous editorial oversight and contributions from experts across academia and government research agencies, these proceedings exemplify the enduring impact of the Berkeley Symposia in shaping the future of mathematical sciences and their application to real-world problems. This title is part of UC Press's Voices Revived program, which commemorates University of California Press’s mission to seek out and cultivate the brightest minds and give them voice, reach, and impact. Drawing on a backlist dating to 1893, Voices Revived makes high-quality, peer-reviewed scholarship accessible once again using print-on-demand technology. This title was originally published in 1972.