The primary goal of this study was to investigate the longitudinal stability and reciprocal relationship between self-directed learning ability, ego-resilience, and career maturity across time using the Seoul Education Longitudinal Study (SELS) panel data of Time 7 (first year of high school), Time 8 (second year), and Time 9 (third year). The autoregressive cross-lagged model (ARCLM) was employed to examine the autoregressive effects of within-subjects variables and cross-lagged effects of between-subjects variables. Results from the ARCLM revealed that previous self-directed learning ability, ego-resilience, and career maturity had significant effects on subsequent self-directed learning ability, ego-resilience, and career maturity, respectively, with stable autoregressive coefficients. In addition, self-directed learning ability of the first-year high school students predicted subsequent ego-resilience of the second-year students, and self-directed learning ability of the second-year students predicted subsequent ego-resilience of the third-year students, whereas ego-resilience did not significantly predict subsequent self-directed learning ability. Furthermore, the cross-lagged effects of self-directed learning ability in relation to career maturity and ego-resilience in relation to career maturity were statistically significant, indicating reciprocal relationships.