Effective citation contributes to the success in master's (MA) thesis writing. The current study investigates cross-disciplinary citation practice in EFL Master's theses. First, the corpus was compiled by collecting 20 Applied Linguistics (AL) and 20 Biology (BIO) MA theses Discussion sections. The forms and rhetorical functions of citations were then identified and quantified. The results show that the writers from the two disciplines have different citation practices. In terms of forms, the AL discipline writers utilized both integral and non-integral forms almost equally. The BIO discipline writers, on the other hand, deployed significantly more non-integral citations. In terms of rhetorical functions, citations were used by both groups to achieve a variety of rhetorical functions. The AL discipline writers utilized citations mostly for Comparison and Application to provide explanation and justification. By contrast, the BIO discipline writers took a more descriptive approach by using more Attribution. Overall, the results suggest that while the AL writers seemed to align their citation forms and functions, the BIO writers adopted a more simplified or descriptive approach when citing. The study offers evidence in the need to guide EFL writers of different disciplines to becoming more strategic in their citation practice.