Methods of treating or preventing an IL-1 related disease or condition in a mammal comprising administering an effective amount of an IL-1.beta. binding antibody or IL-1.beta. binding fragment thereof. An IL-1.beta. binding antibody or IL-1.beta. binding fragment thereof is provided comprising the amino acid sequence of SEQ ID NO:28, and related nucleic acids, vectors, cells, and compositions, and a method of preparing an affinity matured IL-1.beta. binding polypeptide is provided. IL-1.beta. binding antibodies or IL-1.beta. binding fragments thereof are provided which have desirable affinity and potency.