The present study aimed to investigate the use of an Action Research based program (AR) for enhancing EFL general diploma students ' professional knowledge (PK) and attitude at the Faculty of Education. The study adopted a pre-post group design. The study sample was thirty students (the whole group) who were submitted to an intensive training in Action Research based-program. The instruments of the study included a needs assessment questionnaire, a checklist to determine the PK domains and their indicators, a pre-post PK test and a pre-post attitude scale. Analysis of data obtained by students (using t- test) revealed that the AR program was so efficient and effective in promoting EFL general diploma students' PK and attitude in the post-performance of the test and the scale. Discussion of these findings, recommendations and suggestions for further research are presented.