Living cells use “circuits” of interacting molecules to process signals, remember information, and interact with their environments. My team develops two approaches to study the design principles of these biological systems, and to create synthetic systems that can program biomedically useful cellular behaviors. First, we pioneer synthetic biology approaches, in which we design and build molecular circuits from the bottom-up and test their function in eukaryotic cells. Using this approach, we have discovered key principles governing the circuits that control transcription regulation and epigenetic memory, and in turn developed systems for programming gene expression control in therapeutic human cells. Second, we develop new methods to study and harness the process of evolution in the design of biological systems. A central pillar of this effort is “eVOLVER”, an open-source, flexible, and scalable continuous culture platform we invented that is now being used across academic and industry settings to implement custom and automated microbial culture and evolution experiments. Using eVOLVER, we are developing high-throughput methods for the automated continuous directed evolution (CDE) of proteins with radically altered activities and specificities in order to reveal basic insights into protein evolution and enable a new generation of therapeutics.