Synthesis of novel zwitterionic block copolypeptides, poly(N-isopropylacrylamide)-block-poly(L-glutamic acid-co-L-lysine) [PNiPAM(n)(PLG(x)-co-PLLys(y))(m), where n is the number-average degree of polymerization (DPn) of PNiPAM block, x and y are the mole fraction of glutamic acid and lysine residues, respectively, and m is the total DPn of the peptide block], and their stimuli-responsiveness to temperature and pH variation in aqueous solutions are described. Initiated with the amino-terminated poly(N-isopropylacrylamide) (PNiPAM(n)-NH2), ring-opening polymerization (ROP) of a mixture of gamma-benzyl-L-glutamate N-carboxyanhydride (BLG-NCA), and Boc-L-lysine N-carboxyanhydride (BLLys-NCA) afforded the block copolypeptides PNiPAM(n)(PBLG(x)-co-PBLLys(y))(m), with a poly(N-isopropylacrylamide) block together with a random copolypeptide block, which was then deprotected with HBr/trifluoroacetic acid into the double hydrophilic block copolypeptides, PNiPAM(n)(PLG(x)-co-PLLys(y))(m). Their block ratios and lengths, as well as the amino acid residue ratios in the random copolypeptide block are varied (n = 360, x = 0.4-0.5, y = 0.4-0.6, and m = 220-252). The secondary structures of the copolypeptides in aqueous solution at different pH conditions were examined. Phase transitions in aqueous solutions induced by both pH and temperature variation were investigated by H-1 NMR spectroscopy. The transitions induced by temperature were also explored by turbidity measurements using UV/vis spectroscopy for their lower critical aggregation temperature (LCAT) determination. Furthermore, these aggregation processes were followed by dynamic light scattering measurements.