This research study investigated the leadership practices of primary and secondary schools leaders in Nigeria. In investigating the leadership practices of primary and secondary schools leaders in Nigeria, the Leadership Practices Inventory (LPI) instrument (LPI-Self and LPI-Observer) and demographic questionnaire were used to collect data from primary and secondary schools leaders and teachers. The data collected were analyzed based on the five leadership practices identified by Kouzes and Posner, which were: challenging the process; inspiring a shared vision; enabling others to act; modeling the way; and encouraging the heart. The LPI instrument and demographic questionnaire were administered to 50 primary school leaders and 50 secondary school leaders and teachers that were randomly selected. Out of this sample population, 27 primary school leaders and 171 teachers and 24 secondary school leaders and 237 teachers participated. In investigating the leadership practices of primary and secondary schools leaders in Nigeria, 9 research questions and 5 hypotheses were developed, analyzed and tested. The research questions and hypotheses were analyzed using LPI scoring software, LPI normative scale and SPSS^®. Descriptive and inferential statistics [t-tests & ANOVAs] were used to analyze data collected. The findings from this research were: primary school leaders moderately practiced encouraging the heart, inspiring a shared vision and modeling the way while secondary school leaders moderately practiced encouraging the heart, enabling others to act and challenging the process; the leadership practices of primary school leaders differed significantly from the leadership practices of secondary school leaders in challenging the process, inspiring a shared vision and modeling the way; primary and secondary schools leadership practices differed significantly by age groups in challenging the process, enabling others to act, and encouraging the heart; primary and secondary schools leadership practices differed significantly by gender; educational qualifications; and numbers of years in school system.