A bispecific antibody comprising a first antigen-binding domain that binds human CD3, a second antigen-binding domain that binds human CD20, and a chimeric heavy chain constant region tethered to each of the first and second antigen-binding domains, wherein the first antigen-binding domain that specifically binds human CD3 comprises three heavy chain complementarity determining regions (HCDR1, HCDR2, HCDR3) and three light chain complementarity determining regions (LCDR1, LCDR2, LCDR3), wherein (i) A1-HCDR1 comprises the amino acid sequence of SEQ ID NO: 12; (ii) A1-HCDR2 comprises the amino acid sequence of SEQ ID NO: 14; (iii) A1-HCDR3 comprises the amino acid sequence of SEQ ID NO: 16; (iv) A1-LCDR1 comprises the amino acid sequence of SEQ ID NO: 20; (v) A1-LCDR2 comprises the amino acid sequence of SEQ ID NO: 22; and (vi) A1-LCDR3 comprises the amino acid sequence of SEQ ID NO: 24, wherein the second antigen-binding domain that specifically binds human CD20 comprises three heavy chain complementarity determining regions (HCDR1, HCDR2, HCDR3) and three light chain complementarity determining regions (LCDR1, LCDR2, LCDR3), wherein (i) A2-HCDR1 comprises the amino acid sequence of SEQ ID NO: 4; (ii) A2-HCDR2 comprises the amino acid sequence of SEQ ID NO: 6; (iii) A2-HCDR3 comprises the amino acid sequence of SEQ ID NO: 8; (iv) A2-LCDR1 comprises the amino acid sequence of SEQ ID NO: 20; (v) A2-LCDR2 comprises the amino acid sequence of SEQ ID NO: 22; and (vi) A2-LCDR3 comprises the amino acid sequence of SEQ ID NO: 24, wherein the chimeric heavy chain constant region comprises: (i) a human IgG1 or a human IgG4 upper hinge amino acid sequence from positions 216 to 227 (EU numbering); (ii) a human IgG2 lower hinge amino acid sequence comprising PCPAPPVA (SEQ ID NO: 52) from positions 228 to 236 (EU numbering); (iii) a human IgG1 CH1 domain and a human IgG1 CH3 domain, or a human IgG4 CH1 domain and a human IgG4 CH3 domain; and (iv) a human IgG4 CH2 domain amino acid sequence from positions 237 to 340 (EU numbering); and wherein the bispecific antibody exhibits a higher binding affinity for human FcyRIIA relative to human FcyRIIB, and exhibits little or no detectable binding affinity to human FcyRI and human FcyRIII, as measured in a surface plasmon resonance assay. (i) A1-HCDR1 comprises the amino acid sequence of SEQ ID NO: 12; (ii) A1-HCDR2 comprises the amino acid sequence of SEQ ID NO: 14; (iii) A1-HCDR3 comprises the amino acid sequence of SEQ ID NO: 16; (iv) A1-LCDR1 comprises the amino acid sequence of SEQ ID NO: 20; (v) A1-LCDR2 comprises the amino acid sequence of SEQ ID NO: 22; and (vi) A1-LCDR3 comprises the amino acid sequence of SEQ ID NO: 24, (i) A2-HCDR1 comprises the amino acid sequence of SEQ ID NO: 4; (ii) A2-HCDR2 comprises the amino acid sequence of SEQ ID NO: 6; (iii) A2-HCDR3 comprises the amino acid sequence of SEQ ID NO: 8; (iv) A2-LCDR1 comprises the amino acid sequence of SEQ ID NO: 20; (v) A2-LCDR2 comprises the amino acid sequence of SEQ ID NO: 22; and (vi) A2-LCDR3 comprises the amino acid sequence of SEQ ID NO: 24, (i) a human IgG1 or a human IgG4 upper hinge amino acid sequence from positions 216 to 227 (EU numbering); (ii) a human IgG2 lower hinge amino acid sequence comprising PCPAPPVA (SEQ ID NO: 52) from positions 228 to 236 (EU numbering); (iii) a human IgG1 CH1 domain and a human IgG1 CH3 domain, or a human IgG4 CH1 domain and a human IgG4 CH3 domain; and (iv) a human IgG4 CH2 domain amino acid sequence from positions 237 to 340 (EU numbering); and