Interest in the role of extracellular vesicles (microvesicles and exosomes) is expanding rapidly. It is now apparent that far from being merely cellular debris, these vesicles play a key role in cell to cell communication and signalling. Moreover, they are significantly elevated in a number of diseases. This raises the question of their direct role in pathogenesis as well as their possible use as biomarkers. This book stems from the first international meeting on “Microvesicles and Nanovesicles in Health and Disease” held at Magdalen College, Oxford, in 2010. The purpose of the meeting was to bring together, for the first time, a range of experts from around the world to discuss the latest advances in this field. Key to the study of these vesicles is the availability of methodologies for their measurement in biological fluids. A major section of the meeting therefore focused on a range of exciting new technologies which have been developed for this purpose. The presentations at this meeting form the basis of this book, which will appeal to basic scientists, clinicians and those developing technology for the measurement of nanoparticles.