High resolution solid state NMR techniques will be used to obtain detailed microscopic information on molecular conformation, structure, and dynamics of pure and mixed lipid bilayers as well as lipid-peptide interactions, 3lP, 2H and l9F spectra of highly oriented lipid samples will be studied to obtain data on molecular conformation and disorder. The molecular details of the gel-liquid crystalline phase transition in pure lecithins and ethanolamines will be investigated, primarily with 2H NMR, as will the phase behavior and molecular dynamics of certain binary lipid mixtures. Magic angle sample spinning (MASS), powder spectra and spectra of oriented bilayers will be used to investigate the pretransition in lecithins, and similar techniques will be used to study certain basic assumptions regarding chain ordering. Finally, two approaches to obtaining high resolution spectra of peptides in lipid matrices are proposed. Neither involves isotopic labeling of the peptide and neither should suffer from background lipid signals.