The purpose of this study was to investigate the effect of preservice teachers' identity on TPACK regarding the mediating roles of mathematics teaching competency, teacher belief, and technostress across grade levels. A total of 926 preservice mathematics teachers participated in the study. We used structural equation modeling to determine and compare the path coefficients. The results indicated that the effect of teacher identity on TPACK was positive and significant from freshman to senior. In all grades, the mediating effects of technostress and mathematics teaching competency were significant, but the mediating effect of teacher belief was generally insignificant.