Antibodies that bind to polypeptides and peptides comprising the sequence of zalpha11 Ligand as shown in SEQ ID NO: 2 are described. The antibodies may bind the full length sequence of 162 amino acid residues or a fragment thereof, including a mature polypeptide of 131 amino acid residues and smaller polypeptide and peptide sequences. The antibodies may include antibodies that are polyclonal, monoclonal, murine, humanized or neutralizing. Methods for producing the antibodies are also described.