Transporters in Drug Development is a corner stone in a high profile book series on advances in pharmaceutical sciences initiated by AAPS, Springer and Professor Daan Crommelin as series Editor. Transporters in Drug Development: Discovery, Optimization, Clinical Study and Regulation list chapters written by leading researchers in the transporter field from academia, pharmaceutical industry and medicines agencies. The book encompasses examples and advises on how membrane transporters can be dealt with in academic industrial drug discovery and pharmaceutical development as well as from a regulatory perspective. Methods and examples of in vitro characterization of single transporters in intestine, liver and kidney are described as well as characterization of substrate overlap between various transporters. Furthermore, probes and biomarkers are suggested for studies of the transporters impact on the pharmacokinetics of drug substrates/candidates interacting on transporters. The challenges of translating in vitro observed interaction of transporters into in vivo relevance are discussed as well as the perspectives of applying targeted proteomics and mechanistic modelling in this process.