This paper asserts that a gap is developing in English for Special Purposes (ESP) between theory and practice, between received wisdom and grassroots activity that are important to understand when considering the future of ESP. Evidence for these gaps in ESP are discussed in detail in the context of course design, academic input, and the practitioners. Historically, ESP has been the product of two main inputs: theories and research about the nature of language and learning, procedures for course materials and design. It is argued that in a significant amount of recent ESP instruction, there has been a failure to achieve this degree of synthesis. If this problem is to be remedied, more appropriate types of theoretical and practical support for the ESP practitioner need to be developed. Suggestions for implementing such support are offered; they involve teacher development, curriculum design, teaching materials, and academic activity. (Contains 16 references.) (JP)