Synthetic polypeptides or polyamino acids have become a useful and multifunctional platform in advanced drug delivery studies. Nonetheless, the full potential of these systems has yet to be achieved. The final structure of polypeptide conjugates and their in vivo behavior are dependent on an extraordinarily complex pattern of interconnected physico‐chemical and structural parameters, making sophisticated directional design of such systems difficult and often unachievable. In this review, the authors aim to discuss the role of these parameters in the successful design of different drug delivery architectures and to delineate some basic correlations between structure, properties, and the biological behavior of polypeptide‐based conjugates. image