Zeolites are crystallized by a method that involves vapor-phase transport of organics and/or water. Amorphous powders obtained by drying Na2O.Al2O3.SiO2 gels of various compositions are transformed into zeolites by contact with vapors of amines and water, or water alone. It is shown that water and a sufficiently high pH in the reacting, hydrous solid are necessary for the crystallization to proceed. Amines can participate in the crystallization process by absorbing into the reacting, hydrous oxide phase and elevating the pH. In some cases, the amine may also serve as a structure-directing agent. Implications from this novel method of crystallizing zeolites towards the study of zeolite crystallization mechanisms and the synthesis of new materials are discussed.