Abstract: The major purpose of this study is to find out the extent to which previous knowledge of Book-keeping will predict students’ academic performance in Principles of Accounts 1 (BED 111) at the NCE 100 level in College of Education, Ikere Ekiti, Ekiti State, Nigeria. The study employed an ex-post facto research design with a sample of 371 selected from a population of 708. Three research hypotheses were tested at 0.05 level of significant using T-test, Standard deviation, Multiple regression and Analysis of variance. A finding from the study reveals that previous knowledge of Book-keeping significantly contributes to the prediction of academic performance of students in Principles of Accounts 1 (BED 111) among others. It was concluded that the influence of previous knowledge in teaching/learning process provides the background to framework upon which new learning will be placed. It is recommended that Joint Admission Matriculation Board (JAMB) should properly streamline their admission requirements to ensure that only students with O’level result in Book-keeping and Accounts are qualified to apply for NCE Business Education programme.