Effects of adding Y2O3 and La2O3 on the crystallization of beta-quartz solid solution (ss) and the subsequent beta-quartz ss to beta-spodumene transformation of Li2O . Al2O3 . 4SiO(2) glass-ceramic were investigated. Adding greater than or equal to 4 mol% YO3/2 or 8 mol% LaO3/2 effectively improved the control of the crystallization process of the glass. Y2O3 did not effectively induce bulk crystallization of beta-quartz ss, but can reduce the rate of surface crystallization. La2O3 completely suppressed the surface crystallization and promoted a uniform, bulk crystallization of beta-quartz ss. For both the Y2O3- and La2O3-doped glasses, the kinetics for glass crystallization to P-quartz ss was delayed as the doping level increased. Except for the 8 mol% LaO3/2-doped glass in which no beta-spodumene was formed, the kinetics for the beta-quartz ss to beta-spodumene transformation for the doped glasses was enhanced compared with that for the undoped glass. For the 4 and 8 mol% YO3/2-doped compositions, the relative amount of beta-spodumene to beta-quartz revealed an anomalous decrease trend with heating temperature in a particular temperature range. This can be explained by the surface crystallization characteristic, which induced an overlap of crystallization and beta-quartz ss to beta-spodumene transformation. Glass doped with 8 mol% LaO3/2 exhibited an Avrami exponent of about 2.4 and an activation energy for crystal growth of beta-quartz ss of about 418 kJ mol(-1).