This current and five previous volumes (Volumes 133, 135, 144, 155, 178) convincingly demonstrate the vast applications of small rings in modern Organic Synthesis. Such applications range from total syntheses of cyclopropyl-group-containing natural products and non-natural biologically active compounds or compounds with other important properties (e.g. liquid crystalline) via syntheses of cyclopropyl analogues of natural and non-natural physiologically active compounds, e.g. peptidomimetics, to the use of cyclopropyl groups as reactive subunits in so-called composite functional groups. This current volume covers a survey of the wide range of biological activities of cyclopropyl-containing compounds, up-to-date comprehensive reviews on the multiple applicabilities of two multifunctional small ring building blocks - methyl-2-chloro-2-cyclopropylidene acetate and bicyclopropylidene - in Organic Synthesis as well as a striking new approach to cyclopentenones from easily accessible 1-ethynylcyclopropanols, which is rather general and favorably complements other cyclopentenone syntheses.