Quality Education is a vitul instrument fur social, economic, cul/Ura! and other developments of a nut ion. It is a means by which problem-solving and responsible citizens are cultivated. However. quality ofeducation is affected by the complex set of factors. one of' which is teachers· competence. Thus, the Purpose o.f this study was to assess factors affecting quality of' education in relation to teachers' competence. It was aimed at assessing the academic (Subject matter) and professional knowledge level of secondary school teachers and their professional pra,clice (professional application). The major obstacles that hinder teachers from applying their competencies and the possible soluuons as perceived by teachers and instructional leaders were also within the scope of this study. Tl>is studyfollowed a descriptive survey method. Relevant data were gatheredfrom 14'6 students, 49 teachers and 33 instructional leaders. The respondents were selected by using simple random sampling, available and purposive sampling tec"1hiques. Data obtained from questionnaire were analyzed using percentage. and the data from observation and focus group discussion were analyzed qualitatively, all in an integrated manner. The findings of this study showed that although teachers of general secondary schools have the required subiect matter knowledge, their professional knowledge is in its average level in some indicator and low in mus/ of the indicators. Generally there is a problem in the professional knowledge . . Moreover, the professional practice is totally not in line with the expectation of' lv/0£. Teachers. use lecture-dominated approach to teaching where the learners are passive recipients. leaching aids are not being used, the language ability of most teachers is poor, continuous assessment is miss used and etc. Thus, it was suggested thdt measures should be taken according to the problems under discussion: more focus on practical trainingfor prospective graduates, 011 job training/hr those who are teaching in general secondary schools tofill all the gaps in re/a/ion to professional ski/ts. Jn addition to these, Woreda education offices should allocate appropriate budget to produce teaching aids al school. Teachers shou/~o produce teaching aids which are available in their localities.