This timely collection of reviews focuses upon protein secretion systems, their participation in fundamental processes and their contribution to the virulence of important pathogens. There is excellent coverage of the major transport and secretion systems in Escherichia coli, Salmonella enterica and many other Gram-negative bacteria. The type I to V secretion systems are also dealt with separately and written to produce an extensive and valuable resource for protein secretion in Gram-negative bacteria. Researchers investigating Gram-positive bacteria are likely to find this volume to be of less interest though. The excellent chapters that provide an overview of Gram-positive secretion systems and then Listeria monocytogenes and Mycobacterium tuberculosis collectively fall short of providing a comparably extensive resource. For example, the absence of a specific chapter on Staphylococcus aureus is surprising. Despite this, the volume is indubitably a worthy addition to the personal reference collection of every bacteriologist with an interest in host-pathogen interactions.