This study investigated the growth trajectory of academic achievement in Math and English among 519 students in a vocational senior high school in Taiwan. Covering the complete individual learning profile, our dataset included pre-enrollment variables, periodic test scores, and college entrance examination scores. We employed a group-based trajectory model that identified three homogenous subgroups with distinct trajectories of academic achievement in Math and English and demonstrated baseline predictive factors associated with these trajectories as well as relationships between different trajectories and students' college entrance examination scores. Our analysis contributes to the literature in two ways. First, this study demonstrates that when school practices focus on improving or remediating the performance of students in the low-achievement group, the obvious decrease in performance of those in the middle is ignored. Such finding indicates the need for inclusive or specialized practices that enhance the performance of students in all groups. Second, our analysis reveals that pre-enrollment academic preparation appears to be a strong predictor of later academic performance as noted through the reproduction of pre-enrollment academic performance in students' college entrance examination scores. Therefore, upon enrollment, schools should start interventions that reflect the needs of different groups of students.