The proposed work intends to clarify several important problems in condensed matter physics. They include the dynamic and static magnetic properties of surface adatoms at fractional through multimonolayer levels; the mechanism(s) responsible for high temperature superconductivity, in particular the nature of the two-dimensional antiferromagnetism of the type evidenced in the copper oxide high Tc superconductors; the search for new high Tc superconductors; and the nature of strong localization in one- and two-dimensional electromagnetic systems. The research will utilize the techniques of electron spin resonance, direct dc magnetization, weak localization, and atomic scanning and force microscopy for application to these problems.