Elastin-like polypeptides (ELPs) are thermally responsive biopolymers that consist of a repeated amino acid motif derived from human tropoelastin. These peptides exhibit temperature-dependent phase behavior that can be harnessed to produce stimuli-responsive biomaterials, such as nanoparticles or injectable drug delivery depots. As ELPs are genetically encoded, the properties of ELP-based biomaterials can be controlled with a precision that is unattainable with synthetic polymers. Unique ELP architectures, such as spherical or rod-like micelles or injectable coacervates, can be designed by manipulating the ELP amino acid sequence and length. ELPs can be loaded with drugs to create controlled, intelligent drug delivery systems. ELPs are biodegradable, nonimmunogenic, and tolerant of therapeutic additives. These qualities make ELPs exquisitely well-suited to address current challenges in drug delivery and have spurred the development of ELP-based therapeutics to treat diseases-such as cancer and diabetes-and to promote wound healing. This review focuses on the use of ELPs in drug delivery systems.