This study investigated the effects of a career exploration intervention (CEI) on career maturity and self-concept among Malaysian high school students, using a true experimental design (pretest--posttest with a control group). One hundred thirty-nine high school students in Malaysia were recruited and randomly assigned to receive either a CEI or no intervention. Multivariate analyses of covariance showed significant differences in career maturity and self-concept between the experimental and control groups. Career maturity and self-concept were enhanced immediately after the CEI, and the effects were retained after 4 weeks. Students' evaluation and feedback on the intervention were also collected. Research and practice implications are discussed.