Cordierite-based glass ceramics of the 2MgO:2Al2O3:5SiO2 composition with t-ZrO2 (3 mol% Y2O3-ZrO2) and P2O5 addition, was heat-treated isothermally and isochronically for crystallization studies. Major crystalline phases incurred by the heat treatment were t-ZrO2 and α-cordierite. Surface nucleation predominated when edge and corner nucleation in these samples were suppressed regardless of their radii of curvature. Crystallization began with the formation of β-quartz S.S. and its transformation to α-cordierite was followed by prolonged heating. Cellular growth of α-cordierite on the surface of the quenched glass plates, gave a linear kinetics. The activation energy for cellular growth was ∼ 410 kJ mol-1.