Several low-molar-mass alkyl iodides were studied as initiating dormant species in living radical polymerization with organic catalysts. Primary, secondary, and tertiary alkyl iodides with different stabilizing groups (ester, phenyl, and cyano groups) were systematically studied for the rational design of initiating alkyl iodides. The activation rate constants of these alkyl iodides were experimentally determined for quantitative comparison. These alkyl iodides were used in the polymerizations of methyl methacrylate and butyl acrylate to examine their initiation ability in these polymerizations. A telechelic polymer was prepared using an alkyl iodide with a functional group. Alkyl iodides with multi-initialing sites were also studied.