In education, it is commonly believed that the quality of teachers' learning experiences directly affects the quality of their students' learning experiences. Specifically, teachers' continuing learning may bring about positive effects on student learning. For the past ten years or so, research has emphasized the effects of professional development courses on teachers in hard science disciplines. Little attention has been paid to study the influences of those courses on teachers in the 'soft' sciences, such as English language, especially in the area of teaching of writing. Against this background, I undertook a study to investigate how an in-service professional development course influences the teaching attitudes of writing teachers who enrolled on the course and their teaching practice. I argue that the professional development course empowered the teachers with skills useful for the teaching of writing. I also argue that the course positively changed the attitudes of the teachers towards their practice in the teaching of writing. It is suggested that teachers need to engage in continuing professional development to improve the quality of their teaching.