The crystallization behavior of calcium phosphate glass powder with the molar ratio [CaO]/[P2O5] = 0.88, to which 6.38 mol% TiO2 and 10 mol% Al2O3 were added as nucleation agents, was investigated. The results indicate complex crystallization behavior which depends on the powder particle size and the crystallization temperature. In the crystallization temperature range T-c < 900 &DEG;C the surface mechanism of crystallization dominates in the case of all particle sizes ranging from 0-1 mm and the β-Ca2P2O7 phase is formed. At very long annealing times volume crystallization occurs and the TiP2O7 and AlPO4 phases are formed. In the temperature interval T-c > 900 degreesC the dominant crystallization mechanism depends on the particle size. In the size range 0.15-0.5 mm the surface mechanism of crystallization is replaced by the volume one. In the range > 0.5 mm the volume mechanism of crystallization is dominant. The phases beta-Ca2P2O7, TiP2O7 and AlPO4 are formed in that temperature interval for all particle sizes. The additives TiO2 and Al2O3 influence the nucleation and formation of TiP2O7 and AlPO4 but do not influence the formation of beta-Ca2P2O7.