The Second International Transporter Consortium (ITC) Workshop was held with the purpose of expanding on previous white-paper recommendations, discussing recent regulatory draft guidance documents on transporter-drug interactions, and highlighting transporter-related challenges in drug development. Specific goals were to discuss additional clinically relevant transporters (MATEs, MRP2, BSEP) and best-practice methodologies and to re-evaluate ITC decision trees based on actual case studies. The outcome of the workshop will be a series of white papers targeted for publication in 2013.