A new approach to dendrimer property tuning is demonstrated by combinatorial variation of dendrimer branch length and multivalency level, using a large (390 625-member) self-encoded glycopeptide dendrimer library. Ligands for the fucose lectins of Ulex europaeus were identified by screening a combinatorial library of dendrimers with variable arm length (0–4 amino acids) and multivalency (2–5 end groups). The ligands identified by this approach also bind to the fucose lectin LecB (PA-IIL) of Pseudomonas aeruginosa, and might provide a possible starting point to develop anti-infective agents against this antibiotic resistant pathogen which causes lethal respiratory tract infections in cystic fibrosis patients.