The aim of the present study was to examine the effects of Career Information System (CIS) on high school students’ vocational skills self-efficacy, outcome expectations, work hope, career planning, career decision-making difficulties and postsecondary plans. CIS is an internet-based computer system of occupational and educational information designed to help users become more knowledgeable about the labor market and education system, as well as provide career planning support. Students from two high schools participated in the study. Participants at School A were first-year students who completed the Interest Profiler module of CIS. Participants at School B were first-year students who completed the Interest Profiler, IDEAS, SKILLS, Reality Check, and Work Importance Locator modules of CIS. First-year students who did not participate in the CIS intervention served as the control group in both schools. Participants in both schools who utilized the CIS intervention demonstrated a number of significant differences compared to control group participants at posttest. School A treatment participants' vocational outcome expectations and work hope were higher and career decision-making difficulties (i.e. inconsistent information and lack of information) were lower compared to control participants. School A treatment group participants were also more likely to indicate postsecondary educational plans of specialized training, 2-year community college, or 4-year college, instead of no education plans, compared to control group participants. School B treatment participants' vocational skills self-efficacy was significantly higher than control participants at posttest. Treatment group participants at both schools demonstrated more changes in their occupational interests compared to control group participants at posttest. The effects of CIS did not vary as a function of race/ethnicity or socioeconomic status in regards to any of the career outcome variables in either school. Implications for the use of CIS among first-year high school students will be discussed and suggestions for future research will be provided.