The study investigated the influence of in-service training on the job performance of lecturers in colleges of education in North-west Zone, Nigeria. Four research questions were answered and four null hypotheses were tested at 0.05 level of significance in order to determine the influence of conferences, workshops, seminar, and intensive training on the job performance of lecturers in college of education in north-west zone, Nigeria. The study used survey research design. The population for the study was ninety lecturers (90) from the departments of business education at the colleges of education in north-west zone, Nigeria. The whole population was used as the sample size and therefore, no sampling was made for the study. The instrument used for data collection was questionnaire. The data collected was analyzed using mean and standard deviation to answer the research questions. The null hypotheses were tested using regression analysis at 0.05 levels of significance. The study findings revealed that lecturers' conferences, workshops, seminar and intensive training significantly influenced job performance of lecturers. Based on the study findings, it was concluded that in-service training improves lecturers` job performance in colleges of education in north-west zone Nigeria. The study recommended that in-service training should be encouraged for staff in colleges of education to improve their job performance