This study investigates cross-linguistic variation of metadiscourse in the results and discussion chapters of engineering master's theses written in English and Spanish. The analysis is based on a corpus of 200 master's thesis results and discussion chapters: 100 written by L1 English students and 100 written by L1 Spanish students. Using Hyland's (2005a) interpersonal model of metadiscourse, the results and discussion chapters were compared to examine the influence of lingua-cultural contexts of writing on student writer's employment of metadiscoursal resources. Findings of the comparative analysis reveal significant cross-linguistic differences for overall frequency of metadiscourse as well as for most (sub-)categories. The analysis suggests that interpersonal features of writing are inexorably linked to the specific lingua-cultural contexts in which texts are produced and consumed, even within the same discipline and (part-)genre. The paper concludes with some pedagogical implications for L2 writing instruction.