The two-volume set on C-1 Building Blocks in Organic Synthesis critically reviews the state of the art of a wide variety of reactions by which one carbon atom is added to an organic molecule, forming a C-C bond. In spite of the numerous classic reactions of this kind, there has been enormous progress in recent years, especially for those reactions involving catalytic methods. Introduction of substituted methyl groups is a major challenge and only very recently the first catalysts have been discovered that enable the introduction of fluoromethyl groups in aromatics.