The importance of peptidoglycan in forming the basis of the bacterial cell wall has led to many studies investigating its synthesis. The step of cross-linkage via transpeptidation, and its inhibition by penicillins, has been extremely well characterized yet knowledge of the preceding glycosyltransfer reaction remained elusive until recently. The structures of two glycosyltransferase enzymes, catalyzing membrane-based polymerization of the lipid II monomer unit, have presented a means of elucidating the molecular details of this highly desirable antibiotic target. Evidence acquired before the publication of the structures is related here to these new findings, with particular emphasis on the recognition of substrates and inhibitors.