Vocabulary knowledge plays an important role in determining a person's language proficiency level. This study investigates the role vocabulary plays in determining students' performance within research modules at private higher education institutions (HEIs). The discipline-specific vocabulary in this study includes target words, sampled from an undergraduate research module's prescribed textbook. A mixed-method design is used to explain students' challenges and concerns with regard to research modules. An investigation is launched into students' research vocabulary acquisition by administering pre- and post-testing with regular reliability. By measuring the students' research vocabulary acquisition, the effectiveness of the research module's (mostly incidental) learning process is determined. The relationship between the students' research vocabulary acquisition and their research module performance as part of a Bachelor of Education degree (B.Ed.) curriculum is also established. This study contributes to the development of best practices and the advancement of institutional research development across HEI; it also stimulates interdisciplinary engagement within the research field research modules at HEI in South Africa.