We report the preparation of a new water-soluble, nonionic homopolypeptide poly(l-homoserine) as well as poly(l-homoserine) block copolymers with controllable segment lengths. The conformational preferences of poly(l-homoserine) were also determined in both the solid state and in solution. Poly(l-homoserine) is soluble in water and adopts a disordered conformation that makes it a promising addition to the small class of nonionic, water-soluble homopolypeptides with potential for development for applications in biology. Toward this goal, a poly(l-homoserine) containing a block copolypeptide was prepared and found to assemble into micro- and nanoscale vesicles in water.