The present invention is directed to antagonists of CS1 that bind to andneutralize at least one biological activity of CS1. The invention alsoincludes a pharmaceutical composition comprising such antibodies or antigen-binding fragments thereof. The present invention also provides for a method ofpreventing or treating disease states, including autoimmune disorders andcancer, in a subject in need thereof, comprising administering into saidsubject an effective amount of such antagonists.