<DIV>In complex macromolecules, minor modifications can generate major changes, due to self-assembling capacities of macromolecular or supramolecular networks. The authors highlight how the multifunctionality of several materials can be achieved and valorized for pharmaceutical and biopharmaceutical applications. Opening chapters cover the concept of self-assembling, starch and derivatives as pharmaceutical excipients and chitosan and derivatives as biomaterials and as pharmaceutical excipients. Following chapters discuss polyelectrolyte complexes as excipients for oral administration; natural semi-synthetic and synthetic materials, protein-protein associative interactions and their involvement in bioformulations; self-assembling materials, implants and xenografts; and provide conclusions and perspectives.</div>