Several career decision-making models describe an ongoing career decision evaluation process in which career decisions are constantly being re-assessed as individuals gain occupational information and self-awareness. However, the relation between career decision certainty and knowledge of one's chosen career has not yet been adequately examined; in part due to the difficult nature of assessing the latter construct in large samples. The present study objectively measured occupational knowledge in 316 college students; specifically regarding the career each student had reportedly been considering. Objective occupational knowledge of participants' chosen careers significantly related to interest congruence only, and neither variable significantly contributed to variance in career certainty. Results indicated career decision-making self-efficacy partially drives participation in career exploration activities and perceived occupational knowledge, and all three variables in turn contributed to the prediction of career certainty through direct and/or indirect effects. This study was the first to objectively assess college students' knowledge of the careers they were actively pursuing, and the first to examine that construct along with other important career decision-making variables. Implications and future research directions are discussed.