Given the central role of career stress in college students' lives, this research examined whether career stress mediated the relationship between maladaptive perfectionism and career attitude maturity in a sample of 185 undergraduate students in South Korea. The results indicated that career ambiguity stress, as measured by a career stress inventory, fully mediated the relationship between maladaptive perfectionism and career attitude maturity. That is, maladaptive perfectionism correlated with greater levels of career ambiguity stress, and greater career ambiguity stress correlated with an unconstructive level of career attitude maturity. The authors discuss the findings' implications for career counselors in college settings. (Contains 1 table and 1 figure.)