This study investigated the longitudinal effects of below-basic achievement in elementary school on vocational maturity using 1st through 7th year data of the 2013 Korean Education Longitudinal Study. The current study employed the latent growth model to investigate changes in vocational maturity and used time variables indicating measurement occasions from the first year of middle school to the second year of high school; a variable indicating whether the student was classified into the below-basic achievement level while attending elementary school; and family-, student-, and school-related variables. The results showed that the raw scores for vocational maturity (self-understanding, career planning, and attitude toward work) in the below-basic achievement students (the focal group) were lower than those of students who were never classified into the below-basic achievement level (the reference group) across five occasions. However, after controlling for factors, the scores in self-understanding and career planning of the focal group were higher than those of the reference group. Still, in attitude toward work, the scores of the focal group were lower than those of the reference group. These results imply complicated relations among vocational maturity, academic achievement, and other factors. Based on the results, this study suggests implications for future studies regarding vocational maturity and career education in middle and high school.