A bispecific anti-CD3 x CD19 polypeptide complex that contains a first antigen-binding moiety of the polypeptide complex and a second antigen-binding moiety, methods of producing the bispecific anti-CD3 x CD19 polypeptide complex, methods of treating disease or disorder using the bispecific anti-CD3 x CD19 polypeptide complex, polynucleotides encoding the bispecific anti-CD3 x CD19 polypeptide complex, vectors and host cells containing said polynucleotides, and compositions and pharmaceutical compositions comprising the bispecific anti-CD3 x CD19 polypeptide complex are provided.