Provided herein are, inter alia, methods for linking an mRNA molecule to a polypeptide (e.g., a peptide or a protein) by linking the mRNA molecule to a linking amino acid in the polypeptide, or by linking the mRNA molecule to a linking tRNA to which the polypeptide is attached, via reactions not catalyzed by the ribosome, and methods for making polypeptide libraries. Also provided are mRNA-protein complexes and mRNA-tRNA-protein complexes, libraries containing these complexes, and methods of using these complexes.
