Vocabulary knowledge plays an imperative role in developing students' language learning. This paper aimed at investigating the role of Constructive Alignment Theory in promoting vocabulary knowledge among Engineering students. Sixty three first year students at Benha Faculty of Engineering were randomly assigned into two groups: experimental group (n=33) and control group (n=30). Two main instruments were used: academic vocabulary pre-test, and academic vocabulary post-test. Quantitative data analyses were conducted. Results showed that the experimental group students have developed their vocabulary knowledge. It was concluded that the “Constructive Alignment Theory" was effective in promoting vocabulary knowledge of the participants. It was also recommended that the constructive alignment theory is effective in developing language learning in general as it helps students to be aware of their learning strategies and to be responsible of their own learning and in developing vocabulary knowledge in particular. Constructive Alignment Theory should be integrated into vocabulary learning programs.