While thermodynamically stable metal oxides and other solids could be prepared by conventional high-temperature (ceramic) methods, syntheses of the more important meta-stable oxide materials of current interest, such as the zeolites and other microporous solids as well as layered and framework oxides of various kinds require mild, chemistry-based routes that occur at relatively lowtemperatures. Inthis review, we present a brief survey of the emerging chimie douce (soft-chemical) routes which enable synthesis of a wide variety of metastable oxide materials. A distinction is made between topochemical and nontopochemical routes. Ion exchange, intercalation, redox insertion/extraction, and pillaring are examples of topochemical routes; syntheses using sol-gel, hydrothermal conditions, molten salt media, and acid leaching of appropriate precursor oxides belong to the nontopochemical category. In topochemically controlled synthesis, a thermodynamically stable phase is prefabricated by a high-temperature route, which is then transformed into a metastable phase by an appropriate soft-chemical route. Several examples of synthesis of metastable oxides, drawn from the recent literature as well as from the author’s work, are discussed.