The capability of teachers is the intellectual competence as mastery of subjects, knowledge of teaching methode, learning, behavior of individuals, counseling, and knowledge of the administrative class, and knowledge of how to assess learning outcomes, and knowledge of social and other general knowledge. Professionalism is defined as the ability to implement, develop, and create science, technology, and art. Professional lecturers are lecturers who have special competences in their respective fields to carry out teaching, research, and community services. In addition, professional lecturers are also obliged to follow their professional ethics. The ethics include highintegrity, honesty, doing things right, and doing the right things. However, observations that have been done in recent months at an Islamic school reveal that the teacher professionalism in teaching and learning has been declining. It was because some of the cognitive, affective, and psychomotor domains have not shown any good improvement. Therefor the question of this research is "How is the capability teachers in carrying out their duties and responsibilities as a professional teacher in MTsS Ulumudddin?. "What are factors to support the ability of teachers to perform their duties and responsibilities as a professional teacher in MTsS Ulumuddin?. "What are the constraints of teachers in performing their duties and responsibilities as a professional teacher in MTsS Ulumuddin?. " And what are the solutions of teacher in carrying out the duties and responsibilities as a professional teacher in MTsS Ulumuddin?. This study used a descriptive qualitative research which employed the researcher himself as a key instrument in data collection. The researcher used several instruments during the data collection such as tape recorder, camera, stationery, student attendance lists, the administration of lecturers, and others which were considered necessary to provide information. Data collection techniques used were observation, interview, and documentation. Data analysis technique used was interactive model analytical technique from Miles and Huberman which included three concurrent activities: data reduction, data presentation, and conclusion. Techniques to ensure the validity of the data were credibility, member checking, triangulation, transferability, dependability, and conformability. The results of this study indicated that the teacher professionalism at MTsS Ulumuddin was not fully demonstrated well. This was shown by the indicators of teacher professionalism which have been analyzed in depth through