These proceedings are the culmination of the First Yanbian Workshop on Modern Physics, an epoch making event in Korean history that took place in Yanbian, China during 15-18 July, 1990. The meeting was instrumental to bring the active practitioners in the frontier physic together from many parts of the world including for the first time, those from North Korea. This volume contains the most important lectures by experts in Particle Physics, Conformal Field Theory, High-Tc Superconductivity, Phase Transitions, Medium Energy Physics, Astrophysics and Cosmology.