Properly functioning proteins are essential for all processes in living organisms. Our goal is to understand at the molecular level how functional proteins are made. To carry out their functions, proteins must be targeted to the correct location and fold into their native three-dimensional structures. These processes are tightly linked to protein synthesis by the ribosome and require help from molecular chaperones and other cellular machinery for targeting, membrane insertion and folding. We are employing cellular, biochemical and single-molecule approaches to understand these processes at the molecular level.