Following its inception in the 1950s, cell-free protein synthesis made a tremendous impact on the basic life sciences. The use of cell-free systems was key to understanding molecular mechanisms underlying one of the most complicated processes found in nature: protein translation. Since this time, aggressive cutting-edge research and stiff commerical competition have driven the development of a variety of systems with increased productivity, improved protein quality and relatively low production costs. As a result, technology has generated myriad applications that have enabled advances in fields as diverse as systems biology, structural biology, and drug discovery. Cell-Free Protein Expression describes and expands upon many of these applications. The volume has been divided into six main sections. In the first section, many of the most popular sources of cell-free lysates are introduced. The second section focuses on extraordinary advances made in the Escherichia coli-based systems that have enabled reconstitution of the entire translational process, incorporation of post-translational modifications, yield increase, and production of functional membrane proteins. This progress extends the usefulness of cell-free systems into structural biology applications described in the third section and high-content platforms like protein microarrays discussed in the fourth section. The final two sections cover the use of cell-free protein expression technologies in the rational design and directed evolution of proteins within the scientific community.