Here we report on the synthesis, characterization, and solution behavior of poly(L-lysine)-b-polyglycine diblock and triblock copolypeptides in aqueous solution. Several methods including light scattering, conductivity, and microscopy are used to characterize the self-assembly and subsequent structure of the polypeptides in solution. Light scattering and confocal microscopy indicate that the objects initially formed in solution are vesicles whose size depends strongly on the initial processing conditions. As poly(L-lysine) undergoes a random coil – helix transition with pH, the polypeptide is pH responsive and the glycine block possesses a level of fluidity that allows the objects formed in solution to rearrange in response to pH. After multiple pH cyclings, light scattering indicates objects of comparable size (150 nm radius) are formed no matter the initial processing conditions. Circular dichroism results verify that the change in size observed over pH cyclings tracks with the random coil – helix transition of the lysine block.