Polymer materials provide solutions to many pressing biomedical, manufacturing, and environmental challenges. However, traditional polymer materials have a limited capacity for rearrangement, presenting difficulties in their processing, use, and recycling. Engineering reversible interactions within polymer networks enables the formation of dynamic and reconfigurable materials, opening new opportunities for use and re-use of polymer networks. In this talk, we will present fundamental insight and applications of dynamic covalent polymer networks with an emphasis on their utility in biomedical applications. We provide a framework for engineering dynamic covalent macromolecular systems by linking molecular behavior at the reversible junctions to macroscopic properties using modeling, spectroscopy, and mechanical characterization. We then present how we use this knowledge to design dynamic biomaterials for a range of biomedical challenges, including the thermal stabilization of complex biologics, the design of drug delivery systems, and tissue mimics for 3D cell culture.