Featuring 71 papers from the 1991 MRS Spring Meeting (April 29 - May 3, Anaheim, California), this volume focuses on the rapidly expanding scientific interest in growing materials with fundamentally different crystal structures, one upon the other, to achieve a wider range of available thin film materials and heterostructures for novel thin film applications ranging from magnetic recording to high Tc superconductors to novel metal/semiconductor heterojunction devices. Topics discussed include: novel heteroepitaxial systems; growth morphology; in situ and ex situ characterization; epitaxial metastability; interfacial phases and chemical effects; Si/Ge and III-V/Si; and strain effects.