Vocabulary has been considered an essential element in learning a language and, within English for Specific Purposes (ESP), the lack of discipline-specific vocabulary can be identified as an obstacle to student success. The paper reflects upon the experience of teaching ESP at a university, examines students' awareness of vocabulary learning strategies and presents one strategy involving technology and promoting autonomy. The paper compares student performance in three different courses, one being a special course entitled English Autonomously where students select their own content from a prepared list of modules and the others being English for Lawyers and English for Mathematicians. While students choosing a vocabulary building module of English Autonomously have been found to be active seekers and users of a variety of learning strategies, students of two other courses need more help with looking for effective ways of developing their vocabulary. The application Quizlet can be successfully employed within language courses and it proved to be efficient in both English for Lawyers and English for Mathematicians courses. Apart from activities with flashcard sets, two specifically designed Quizlet tasks assisted students with broadening their technical vocabulary knowledge: providing example sentences and generating practice for reading mathematical expressions.