This study reports on the development of ESP (English for Specific Purposes) multimedia courseware on oral presentations, and its integration into self-study learning and elective courses for students with different English proficiencies, as one solution to problems in ESP courses in Taiwan. The courseware design is based on Mayer's multimedia learning cognitive theory, and the language learning focus draws on Chapelle's suggested criteria for development of multimedia CALL. Evaluation of student performance with two different formats for courseware integration is based upon data from pre- and post-tests for preparing speech texts, and a questionnaire survey. The courseware provides authentic materials with a logical situational layout and a friendly interface design for learning ESP for oral presentations in international business and technical settings and offers rich and flexible learning activities with corresponding on-line self-evaluation so that students actively engage in cognitive processing. Students with different English proficiencies have different concerns about giving a presentation. Meanwhile, after students' self-study for six weeks, regardless of level of proficiency, students' learning effectiveness and satisfaction with the courseware integration were significantly improved, by qualitative and quantitative analysis. Such students' improvement suggests success of the courseware design and learning effectiveness with its integration. (Contains 8 tables and 4 figures.)