Due to the low academic performance of Liberian students, in 2013, the president of Liberia declared that the education sector needed to be overhauled. Consequently, the education minister launched a nationwide professional development (PD) program. Despite the PD initiatives, academic performance in an urban school district (USD, a pseudonym) has not improved. The purpose of this qualitative study was to explore Liberian secondary teachers' perceptions on the strength, weakness, and recommended improvements of the PD at USD. The theoretical framework that guided the study was Mezirow's transformational learning theory. The key research questions were focused on the secondary school teachers' perceptions of the existing PD. A basic qualitative research design was used to conduct interviews with eight secondary school teachers who have attended at least two PD sessions. Thematic analysis technique was applied to code and analyze the data. The findings showed weakness and strength in separate aspects of the USD PD. Salient data revealed a need for the existing PD to be revised to be in sync with widely used adult learning theories. The findings from this research can lead to positive social change when used by stakeholders to understand and change the perceptions of teachers and improve their teaching skills. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]