The past decade has seen growing interest in the investigation of self-assembling nanostructures, particularly in aqueous solution. In this context, polypeptide-based copolymers show considerable promise as building blocks that allow enhanced control over intra- and intermolecular interactions, in concert with stable, yet modifiable, secondary and tertiary structures. We will focus here on the most recent advances in the formation of micelles and vesicles from peptide-polymer conjugates or from copolypeptide systems, and on the capacity of these structures to manifest stimuli-driven variation in size and shape. We will also discuss a new generation of materials based on protein-like copolymers that offer precise control over molecular composition and structure along with predetermined biological functionality.