The Third International Seminar for Hydrology Professors was held at Purdue University in Lafayette, Indiana. There were 72 U.S. participants from 25 States and 19 participants from 15 other countries as follows: three from Canada; two each from Costa Rica and Peru; and one each from The Republic of China, Colombia, El Salvador, France, India, Republic of Korea, Mexico, New Zealand, Portugal, Romania, Turkey, and the United Arab Republic. Seventy-eight of the participants were college or university professors and 13 represented various state and national research and technical agencies.