Career preparation behavior has become more important than ever for the successful careerdevelopment of college students in this time of unemployment crisis. This study explored therelationships among college students' perception of career barriers, social support, careerself-efficacy, and career preparation behavior. 1,197 students of 18 junior colleges and 4-yearuniversities filled out self-administered questionnaires, and data were analyzed with SPSS 18.0. Theresults are as follows. First, male students, freshmen, students of poor economic status, and juniorcollege students vs. 4-year university students perceived that they have more career barriers. Malestudents, seniors, middle-class students, and 4-year university students showed higher scores insocial support, career self-efficacy and career preparation behavior. Second, perceived career barriersand social support influenced college students' career preparation behavior in opposite ways; thehigher the perceived social support, and the lower the perceived career barrier, the higher the careerpreparation behavior of college students. Third, career self-efficacy partially mediated the influenceof career barriers and social support on career preparation behavior. The study results suggest thatthe understanding of the interaction between intra-personal and environmental factors is critical toreinforce college students' career preparation behavior.