pADL-pIII-1 is a phagemid vector designed for phage display on the N-terminal side of the protein III of the filamentous bacteriophage M13 or equivalent. This vector contains a PelB leader sequence for expression in the periplasm, a double-SfiI cloning site to introduce scFvs or Fab fragments, a HIS tag for purification and an amber codon located before the full-length copy of the gene III sequence. On non-suppressive bacterial strains, free scFvs or Fab fragments are produced in the periplasm where they can be assayed for binding or purified for further testing. Expression of the fusion is under the tight control of a lac promoter. A strong transcriptional terminator upstream from the promoter efficiently represses undesirable expression and prevents promoter leakiness in absence of induction, thus limiting negative selection against clones bearing toxic products.