This thoroughly revised and updated edition of a widely used practical guide to flow cytometry describes in step-by-step detail an array of time proven and cutting-edge techniques much needed in today's advanced laboratories. These readily reproducible methods deploy emerging flow cytometry technologies in many new applications, especially in the field of stem cells, functional genomics and proteomics, and microbiology. Here, the aspiring investigator will find methods for the characterization of stem/progenitor cells by monitoring the efflux of fluorescent dyes and the elucidation of signal transduction pathways using phospho-specific antibodies. There are also techniques for monitoring gene transfer and expression using fluorescent protein technology, high throughput screening for discovery of novel protein interactions, phenotypic and functional characterization of T cell subsets and precursors, and microbial flow cytometry, to highlight but some of the many useful procedures.