[figure: see text] beta-Lactams were prepared on solid phase starting from serine, threonine, or other beta-hydroxyacids derived from naturally occurring amino acids and a resin bound hydroxylamine. The ring closure was carried out under Mitsunobu conditions. The amino group present on the beta-lactam was used to assemble a short peptide. After a reductive cleavage with Sml2, beta-lactam-containing peptides were obtained.