Described herein are methods for the efficient production of a heteromultimeric protein, such as a bispecific antibody. Heteromultimeric proteins may be capable of specifically binding more than one target molecule or different epitopes on a single target molecule. The methods modulate parameters to improve assembly of the heteromultimeric proteins at higher yield and efficiency than otherwise possible. Also described are compositions comprising a hinge-containing polypeptide, such as a half-antibody.