This study investigates teachers' professionalism and professional development practices which still have lower quality based on the law and do not produce an improved performance yet in South Sulawesi, Indonesia. This investigation focuses on teachers' behavior-attitude, pedagogic skills, and diversity learning activities through effective professional development as commitment to do continuous improvement. The supporting factors and the constraints of being professional teacher are also identified. The design of this study employs exploratory mixed method design with triangulation approach. Simple random sampling is occupied in choosing 331 samples out of 2367 population to answer the questionnaires. While twelve teachers were selected using purposive sampling for interview and observation. The t-test and Anova analysis show that gender has significant different in behavior-attitude practice, while education professional qualification is significant on both behavior-attitude and teachers' learning activities. The qualitative findings show the need to display exemplary behavior-attitude, strength teaching skill, knowledge and beliefs through diversity learning activities in effective professional development. Teacher professional development needs supporting on policy, moral, infrastructure, and financial that can lead teachers to be professional. This study has provided a model of teacher professional development as an input for improving the quality practice of teacher professionalism and professional development in Indonesia, particularly in South Sulawesi province.