This study examined job satisfaction and self-efficacy of library personnel as determinants of their job performance. A descriptive survey research design was adopted for the study. Total enumeration was used to cover 112 library personnel using structured questionnaire. The data collected were analyzed using descriptive statistics. Four research questions were answered in the study. Result obtained indicated that, the levels of job performance, job satisfaction and self-efficacy of library personnel in universities in Southwest Nigeria were high. Job satisfaction has the highest relative contribution to the job performance of library personnel. Among what the paper recommends is that, that good working condition should be put in place so as to sustain the high level of job motivation and job satisfaction among the library personnel in universities in particular and other higher institutions of learning in Nigeria.