An English for Special Purposes (ESP) program, devised for students of the School of Environmental Design at the English Language Centre of King Abdul Aziz University, Jeddah, is described. The course is intended to be of direct relevance to students by developing their English language skills and giving them a basic professional vocabulary. A topic and task approach was devised in order to unite the three demands of an ESP program, namely linguistic, conceptual, and methodological needs. Six principles of the topic and task approach are outlined as follows: (1) the content, derived from the discipline, must be relevant to the learner's purpose; (2) one learns by doing; (3) the language is perceived by the learners as a necessary means to a desired end; (4) error is tolerated and even encouraged; (5) there is a focus upon language as the need arises; and (6) attention is paid to the learner's expectations, previous knowledge, and learning styles. It is indicated that the principles are made operational through the topic and task approach, which lays equal stress upon content and methodology. The actual program is described with regard to its structure, and the way topic and task are integrated in projects. The problems of generalizability, specific or general content and methodology, teacher competence, and evaluation are discussed. (AMH)