Anti-human IL20 monoclonal antibodies that can reduce IL20 mediated activation of both IL20R1/IL20R2 and IL22R1/IL20R2 receptor complexes in one or more species, including humans, are described, as well as antigen-binding molecules such as, e.g., antigen-binding antibody fragments, antibody derivatives, and multi-specific molecules designed or derived from such antibodies, and methods or producing such antibodies or other antigen-binding molecules. Such antibodies or other antigen-binding molecules can be used for treating various diseases and disorders, including autoimmune or inflammatory diseases or disorders.