This is the eighth volume (out of a projected ten) with papers which appeared during the "Stochastic Equations and Their Applications" year (1985-1986) at the Institute for Mathematics and its Applications at the University of Minnesota. This volume, which is directed towards researchers in applied mathematics, engineering, and physics, contains contributions by: M. Aizeman, R. Holley, M. Bramson, D. Griffeath, D.C. Brydges, J.T. Chayes, L. Chayes, J.T. Cox, R. Durrett, R.H. Schonmann, S. Goldstein, L. Gray, J.W. Halley, R. Holley, H. Kesten, T.M. Leggett, C.M. Newman, H.E. Stanley, D. Stauffer, and J.C. Wierman.