This study investigated the effect of in-service education and training (INSET) courses on grade
11 EFL teachers’ knowledge base employing Kirkpatrick’s four-level (reaction, learning, behavior,
result) evaluation model (Kirkpatrick & Kirkpatrick, 2006). To this end, the researchers designed
a study at four stages. At the first stage, a standardized questionnaire, English language teachers’
knowledge base (ELTKB), was administered to thirty 11th grade teachers to examine their views
regarding the INSET classes (reaction). Then ten teachers were interviewed, and their classes were
observed to explore to what extent the INSET courses had affected teachers’ perceptions and actual
job performance (learning). In the next step, 126 students filled in the students’ questionnaire (SQ)
regarding their perception of their teachers’ teaching performance in the English classes before and
after their attendance in INSET classes. At the final stage, the performance of the 126 students on
a language proficiency test was measured to study to what extent their teachers’ performance had
affected their achievement. The result of the ELTKB questionnaire, SQ, interviews, and observations
revealed the beneficial role of INSET classes in teachers’ reaction, learning, and behavior. Moreover,
the result of the program was positive since grade 11 students’ language learning improved after their
teachers’ INSET class attendance. This program evaluation can be illuminating for stakeholders,
policymakers, and curriculum designers.