Professionalism is widely thought to be desirable in ELT, and at the same time institutions are taking seriously the need to evaluate their teachers. This article presents a general approach to professionalism focused on the accountability of the professional to the client based on TESOL's (2000) classification of adult ELT within eight general service areas. Both TESOL's attempt to ascribe Indicators, Measures and Performance Standards to those areas of service and recent attempts to form professional bodies in ELT are shown to be unable to provide effective protection of clients' interests. Nevertheless, the TESOL approach to defining a full ELT service can be modified to adopt a client's perspective, leading to a proposal for a more complete and accountable professional ELT service. The analysis presented here will be of interest to all ELT practitioners seeking to understand the professional context of their own practice and how it may be evaluated.