We report the creation of alkylated poly-N-substituted glycine (peptoid) mimics of antimicrobial lipopeptides with alkyl tails ranging from 5 to 13 carbons. In several cases, alkylation significantly improved the selectivity of the peptoids with no loss in antimicrobial potency. Using this technique, we synthesized an antimicrobial peptoid only 5 monomers in length with selective, broad-spectrum antimicrobial activity as potent as previously reported dodecameric peptoids and the antimicrobial peptide pexiganan.