The current dissertation focuses on the investigation of the beliefs of in-service ESP

teachers in Greek public post-secondary and higher education institutions concerning

the practices employed for enrichment of knowledge of discipline and knowledge of

language use in the specific discipline, and the effectiveness of the practices in relation

to knowledge as well as self-efficacy development. This exploratory study addresses a

rather uncharted area in the Greek context, which makes its contribution valuable to the

established knowledge in its field and responds to the increasing need of ESP teachers

for teacher development. In particular, the research is intended to identify the presence

of the practices employed for knowledge enhancement and the extent to which

engagement with these practices promotes knowledge of discipline and knowledge of

language use, as well as the extent to which they are linked with ESP teachers’ self

efficacy levels. To this end, quantitative research was conducted, employing a specially

designed questionnaire was constructed as the methodological tool for data collection.

The results indicate that the majority of the practices under investigation, are largely

not employed, as a great number of ESP teachers have not engaged with them. In

addition, the findings shed more light onto the extent of effectiveness of each practice

based on ESP teachers’ self-reported answers. Finally, teacher development courses

implications for this branch of teachers are presented and it is suggested that teacher

development courses should be coordinated carefully and be integrated with specific

practices that are expected to lead to supreme enrichment of knowledge and elevation

of ESP teachers’ self-efficacy levels, and thus increase their effectiveness.