In response to globalization and as an adaptive means to 2030 bilingual nation policy, English mediated instruction (EMI) is an emerging phenomenon in higher education in Taiwan and has received energetic discussions, exploring its potential to attract international students and boost domestic students' international competence. However, there is still a distinct lack of evidence in support of EMI courses’ effectiveness on a synchronic improvement of students’ content and language learning. To fill this gap, this study conducted a survey with both quantitative and qualitative questions with the recruitment of ninety-four non-English major college students in a private university in northern Taiwan. The questionnaire started from a draft, was then reviewed by two teacher reviewers and a student reviewer before it was finalized. Three groups of questions were devised to correspond to three research questions and to elicit the student participants’ perceptions of the EMI courses they attended. Regarding the effectiveness of EMI courses on content learning, quantitative data showed that slightly more than half of the participants disagreed. However, qualitative data revealed that the participants did agree upon a need for EMI courses and believed that EMI courses would be helpful. Their disagreement stemmed more from concerns of an extra burden of using English and stress on comprehending terminologies in their major fields. In other words, once the students' concerns could be addressed, using English as a teaching language itself would not be an issue. Regarding the effectiveness of the EMI courses on language learning, it was positively accepted by the participants, and both listening and speaking skills were rated as being improved. Writing was the least trained language skill. Major factors influencing the students’ choices of EMI courses centered on the course content and teaching styles rather than the teaching language. The findings of this study overall supported the further promotion of EMI courses on campus and provided a base for both course design and pedagogical implications. Contrary to a provision of adaptive courses proposed in previous studies, it was suggested here that no separate adaptive courses be needed. Instead, adaptive teaching strategies should be discussed and applied to transform the regular teaching to EMI. Also, apart from a confirmed need for translanguaging, a specific description of desirable teachers’ classroom translanguaging was proposed. It seemed essential that core terminologies be delivered bilingually to guarantee students’ comprehension and that translanguaging make up no more than one-fourth of the teaching language and occur only with the teaching of core terminologies. Other adaptive strategies included a slowed speech speed and necessary repetition. This study also proposed that the discussion of EMI courses not be limited to whether or what courses should be taught in English, but extend to and center on how the target content could be successfully delivered in English by a teaching cohort, the majority of whom are non-native English speakers.