The past two years have been a time of dramatic growth in the field of organic and printable electronics. This review summarizes the most recent advances in the design, application, and understanding of semiconducting materials relevant to this technology. Pentacene, other organic molecular solids, solution-deposited oligomers and polymers, and higher mobility inorganic and nanostructured materials are discussed. In addition, scientific investigations of single-crystal properties and contact barriers are covered, and the most advanced organic-based circuits are pointed out.