In recent years, Taiwan and other East Asian countries have begun to promote English-medium instruction (EMI) at the tertiary level. Communicating through English in EMI classrooms is a basic requirement for English as a foreign language (EFL) learners, but it can be a challenge. Speaking a foreign language is a complex process that involves linguistic competence, speaking skills, and strategy use. Speaking strategies have been viewed as first aid devices used for interaction and communication, to address problems or breakdowns, and to remain active in communication. The purpose of this article is to investigate university students' anxiety, strategy use, and difficulties when speaking English in full and partial EMI contexts. This research involved a large-scale questionnaire survey of 638 students. The quantitative analyses were conducted through a multivariate analysis of variance, a hierarchical multiple regression, and chi-square tests of independence. The results indicated that students receiving partial EMI exhibited high speech anxiety, a lack of confidence, and negative feelings toward English learning. Additionally, students in the partial EMI context were found to use rehearsal and paraphrasing strategies less frequently than those in full EMI contexts. Furthermore, a relationship was observed between the EMI context and difficulties in speaking reported by students.