This study assessed teachers‟ professional development practices in influencing teaching process in Tanzania specifically in Tarime Town Council. The study had four specific objectives namely; to examine the current status of secondary school teachers‟ professional development, to determine the influence of teachers‟ professional development in teaching, to identify the challenges facing secondary school teachers‟ professional development and to establish strategies to improve secondary school teachers‟ professional development. The study employed mixed research approach whilst, convergent parallel design which have both elements of quantitative and qualitative was used. The study involved 68 respondents who were; 1 town education officer, 4 ward education officers, 4 heads of school and 59 teachers and they were obtained through simple random and purposive sampling. Data were collected through questionnaire and interview. Quantitative data were analyzed through percentage and frequencies while the data gathered through interview were analyzed according to the themes identified. The findings revealed that the practices of TPD influences teaching in following areas; pedagogical competence, subject knowledge, and performance of students. However, the current practices were discovered to be insufficient to equip teachers with necessary knowledge and skills as professionals. Based on the findings, the study concludes that, for the good outcome of education teachers‟ professional development should be enhance. The study recommends that, the town and ward education officers together with the heads of school have to establish school-based TPD so as to enable teachers continue learning.