Inclusions in Prokaryotes -- Prokaryote Inclusions: Descriptions and Discoveries -- Bacterial Sulfur Globules: Occurrence, Structure and Metabolism -- Acidocalcisomes and Polyphosphate Granules -- Bacterial Glycogen Inclusions: Enzymology and Regulation of Synthesis -- Biogenesis and Structure of Polyhydroxyalkanoate Granules -- Wax Ester and Triacylglycerol Inclusions -- Cyanophycin-an Ideal Bacterial Nitrogen Storage Material with Unique Chemical Properties -- Insecticidal Protein Crystals of Bacillus thuringiensis -- Protein Inclusion Bodies in Recombinant Bacteria -- Cameos of Selected Additional Inclusions -- Vacuoles -- The Unique Role of Intracellular Calcification in the Genus Achromatium -- Metal Inclusions in Bacteria -- Inclusion Proteins fromother Insecticidal Bacteria -- R-bodies. In prior coverage of prokaryote inclusions (Pankratz and Bowen 1963; Lang 1968; Shively 1974; Allen 1984; Shively et al. 1988; Jensen 1993; Shively et al. 1998) all of the authors appeared to use a broad de?nition of "inclusion", i. e. , a discrete, particulate, separate body in the cytoplasm of the prokaryotic cell. As we carefully searched the literature and began considering topics for this volume, it became obvious that in order to stay within an appropriate length, a more restrictive de?nition of "inclusion" needed to be invoked. This necessity was brought about primarily by two factors, the expansion of the number of "discrete, particulate, separate bodies" described, as well as the apparent wealth of material published on both the earlier and more recently discovered structures in prokaryotes (see material in this Volume as well as Volume 2 of the series Microbiology Monographs). Thus, for this volume, we rede?ned "inclusion" as "a discrete body resulting from synthesis of a metabolic product/reserve. " Further explanation of the de?nition can be found in Chapter 1 and will become clearer as the reader - amines ensuing chapters. Using this new de?nition, we selected eight topics for chapters: sulfur globules, polyphosphate granules and acidicalcisomes, gly- gen inclusions, polyhydroxyalkanoate granules, wax ester and triacylglycerol inclusions, cyanophycin inclusions, insecticidal protein crystals, and protein inclusion bodies of recombinant bacteria.