A diabody comprising a first polypeptide chain and a second polypeptide chain, wherein said first and second polypeptide chains form a covalently bonded complex, and wherein: said first polypeptide chain comprises a VL Domain of a first immunoglobulin, a VH Domain of a second immunoglobulin, and a charged cysteine-containing Heterodimer-Promoting Domain comprising the amino acid sequence of SEQ ID NO:12; and said second polypeptide chain comprises a VL Domain of the second immunoglobulin, a VH Domain of the first immunoglobulin, and a charged cysteine-containing Heterodimer-Promoting Domain comprising the amino acid sequence of SEQ ID NO: 13; wherein said charged cysteine-containing Heterodimer-Promoting Domain of said first polypeptide chain is separated from said VH2 by a polypeptide linker consisting of the amino acid sequence of SEQ ID NO: 2, and said charged cysteine-containing Heterodimer-Promoting Domain of said second polypeptide chain is separated from said VH1 by a polypeptide linker consisting of the amino acid sequence of SEQ ID NO: 2; and wherein said charged cysteine-containing Heterodimer-Promoting Domain of said first polypeptide chain and said charged cysteine-containing Heterodimer-Promoting Domain of said second polypeptide chain are covalently bonded to one another via a disulfide bond between the amino acid sequence of SEQ ID NO: 12 and the amino acid sequence of SEQ ID NO: 13. wherein said first and second polypeptide chains form a covalently bonded complex, and wherein: said first polypeptide chain comprises a VL Domain of a first immunoglobulin, a VH Domain of a second immunoglobulin, and a charged cysteine-containing Heterodimer-Promoting Domain comprising the amino acid sequence of SEQ ID NO:12; and said second polypeptide chain comprises a VL Domain of the second immunoglobulin, a VH Domain of the first immunoglobulin, and a charged cysteine-containing Heterodimer-Promoting Domain comprising the amino acid sequence of SEQ ID NO: 13; said first polypeptide chain comprises a VL Domain of a first immunoglobulin, a VH Domain of a second immunoglobulin, and a charged cysteine-containing Heterodimer-Promoting Domain comprising the amino acid sequence of SEQ ID NO:12; and said second polypeptide chain comprises a VL Domain of the second immunoglobulin, a VH Domain of the first immunoglobulin, and a charged cysteine-containing Heterodimer-Promoting Domain comprising the amino acid sequence of SEQ ID NO: 13; wherein said charged cysteine-containing Heterodimer-Promoting Domain of said first polypeptide chain is separated from said VH2 by a polypeptide linker consisting of the amino acid sequence of SEQ ID NO: 2, and said charged cysteine-containing Heterodimer-Promoting Domain of said second polypeptide chain is separated from said VH1 by a polypeptide linker consisting of the amino acid sequence of SEQ ID NO: 2; and wherein said charged cysteine-containing Heterodimer-Promoting Domain of said first polypeptide chain and said charged cysteine-containing Heterodimer-Promoting Domain of said second polypeptide chain are covalently bonded to one another via a disulfide bond between the amino acid sequence of SEQ ID NO: 12 and the amino acid sequence of SEQ ID NO: 13.