Amino acids, peptides, and proteins are elementary components of the natural world. They play an important role in metabolism and are involved in many different biological adhesion and coating processes in the living environment. The adhesive chemistry practiced by mussels, their rapid, strong, tough, underwater, and seawater resistant adhesion has fascinated generations of adhesive application engineers, researchers, experts, and specialists. Their natural origin, their renewability, their widespread and easy availability, and good biodegradability make them interesting for contemporary adhesive and coating applications.