CD20 is a transmembrane protein of the tetra-spanin family expressed on the surface of B-cells and has been found on B-cells from peripheral blood as well as lymphoid tissues. CD20 expression persists from the early pre-B cell stage until the plasma cell differentiation stage. Conversely, it is not found on hematopoietic stem cells, pro-B cells, differentiated plasma cells or non-lymphoid tissues. In addition to expression in normal B-cells, CD20 is expressed in B-cell derived malignancies such as non-Hodgkin's lymphoma (NHL) and B-cell chronic lymphocytic leukemia (CLL). CD20 expressing cells are known to play a role in other diseases and disorders, including inflammation. The present invention includes anti-CD20 antibodies, forms and fragments, having superior physical and functional properties; immunoconjugates, compositions, diagnostic reagents, methods for inhibiting growth, therapeutic methods, improved antibodies and cell lines; and polynucleotides, vectors and genetic constructs encoding same.