The main purpose of this study was to explore school based continuous professional development (CPD) with reference to its practices and challenges in some selected secondary schools of Bale Zone, Oromia . To achieve the purpose of the study, quantitative research method more specifically a descriptive cross-sectional survey research design was employed. Simple random sampling technique was used to approach individual samples. One hundred thirty six samples, of which (114 teachers, 9 principals, 9 school CPD facilitators, 3 woreda education supervisors and one zonal education experts) were used for the study. Questionnaire was employed as an appropriate data gathering tools. Questionnaires were administered to One forty six samples and one hundred thirty six sample respondents were properly filled and returned the questionnaires and used for analysis. Then, the information gathered through closed-ended questionnaire was analyzed using frequency, percentage, mean and standard deviation while the data gathered through open-ended questions were analyzed qualitatively by means of narration, direct quotation and paraphrasing of the repose of the respondents. The findings of the study indicated that practices of school based professional development activities such as induction, mentoring, coaching, portfolio development, conducting action research, and an overall implementation processes associate with CPD were inadequate. Time constraints, lack of common understanding of partners on CPD, lack of adequate awareness among teachers, absence of clearly defined objectives, turnover of CPD facilitators, the absence of link between CPD and teachers career structure, insufficient budget and absence of giving feedback on CPD activities were identified as major challenges hampering effective implementation of school based Continuous Professional Development in secondary schools under the study. To tackle these problems identified, prior orientation of teachers and all school partners on overall packages of CPD like induction, mentoring coaching, and action research, portfolio activities; allocating sufficient budget and resources used for effective implementation of CPD are recommended. Key terms: Continuous Professional Development, Induction, Mentoring, Coaching, Action research, Portfolio, practices and Challenges. DOI : 10.7176/JEP/10-31-03 Publication date: November 30 th 2019