A method for identifying shampoo-resistant hair-binding peptides is described. The shampoo-resistant hair-binding peptides bind strongly to hair from a shampoo matrix and are stable therein. Peptide-based benefit agents, such as peptide-based hair conditioners and hair colorants, based on the shampoo-resistant hair binding peptides are described. The peptide-based hair conditioners and hair colorants consist of a shampoo-resistant hair-binding peptide coupled to a hair conditioning agent or a coloring agent, respectively. Hair care and hair coloring product compositions comprising these peptide-based hair conditioners and colorants are also described.