In this three-year U.S.-Yugoslav cooperative research project in particle physics between Svjetlana Fajfer of the Institute of Physics, Sarajevo, and Robert J. Oakes at Nothwestern University, the investigators will extend their research in theoretical elementary particles. They will focus on composite models of quarks and leptons and study the unification of fundamental forces among these particles. Their work will advance our knowledge in the general area of high energy physics. This project was approved by the U.S.-Yugoslav Joint Board on Cooperation in Science and Technology and is supported through a joint fund consisting of matching contributions from the governments of the United States and Yugoslavia. The U.S. contribution is provided annually by the Department of State. No NSF funds are involved. Grants are made to the principal scientific institution in Yugoslavia, but include dollar funds for U.S. scientist travel to Yugoslavia and for Yugoslav scientists' living expenses in the U.S.