This study examined instructional methods employed by secondary school English language teachers in classroom to develop students’ English writing skills in Iringa Municipality, Tanzania. Specifically, the study sought to assess English language teachers’ understanding of the purpose of English language syllabus for secondary education; to investigate the teaching and learning techniques used by teachers in classroom to develop students’ English writing skills; and to evaluate the effectiveness of the techniques used in developing English writing skills among students. The social-cultural theory and communicative competence theory were adopted to guide the study. The study employed an interpretivism paradigm, qualitative approach and a phenomenological research design. The study involved 33 participants (12 English teachers and 21 FIII students) who were selected purposively from 3 public secondary schools in Iringa Municipality. The data were collected using documentary review, classroom observations, and interviews, and thematically analysed. The findings revealed that teachers had differing understanding of the purpose of the English syllabus. Also, the findings showed that teachers used techniques, such as explanation and demonstration, writing practice and exercise, reading-writing integration, sentence combining, genre-based instruction, and collaborative writing, in teaching English writing skills. Moreover, the study found that the techniques used were ineffective to develop students’ English writing abilities as many students struggled to write in English. The study concludes that the opposing understanding of the purpose of the subject syllabus among teachers limits teachers from effectively using instructional methods to develop writing skills in English among students. Therefore, teachers should be trained on the purpose of the subject syllabus to enable them effectively use instructional methods in a manner that focuses to develop English writing skills among students per requirements of the subject syllabus