The study investigated the beliefs expressed by a sample of 206 Polish and Spanish teacher-trainees about the use of learners' native language (L1) in teaching English as a foreign language (EFL). Quantitative and qualitative data from a questionnaire revealed considerable differences between the two nationality groups in their beliefs about both medium-oriented and framework-oriented functions of the L1 in an L2 classroom. Moreover, significant differences were found in the participants' accounts of their prior EFL learning experience in terms of the L1-L2 proportion in teachers' classroom language use. A possible interpretation of these findings relates trainees' beliefs to the L2 educational cultures prevalent in different countries, pointing to a contextually-mediated complexity of teacher-trainees' belief systems. The study adds to the existing research on the issues underlying L1 use in L2 teaching that are currently under debate by offering a cross-national comparison of teacher-trainees' beliefs about the place of the L1 in L2 instruction.