This volume provides a comprehensive annual review of the literature published on this subject between July 1999 and June 2000. Coverage includes phosphines and their chalcogenides, phosphonium salts, low coordination number phosphorus compounds, penta- and hexa-coordinated compounds, quinquevalent phosphorus acids, nucleotides and nucleic acids, ylides and related compounds, phosphazenes and the application of physical methods in the study of organophosphorus compounds.