The value and role of concordancers (simple computer programs that can quickly analyze electronic texts to find occurrences of a given word, part of a word, or phrase and display it within its immediate context) in secondary school English-as-a-Second-Language (ESL) teaching are examined. First, their use in higher education is discussed, including their role in syllabus design, evaluation of existing course materials, preparation of print instructional materials, and classroom use by students. The kind of language corpus needed for secondary school instruction is then considered, and factors, both instructional and technical, in compilation of an appropriate corpus are noted. Finally, advantages and constraints of use in secondary level instruction are outlined. The primary advantage is seen as the concordancer's potential role in student empowerment and as a tool for autonomous and advanced learning. Constraints identified include cost, limited space for computers, classroom time limitations, and need for change in student and teacher attitudes toward computers. It is concluded that concordancers can be useful at the secondary school level, with careful planning and appropriate teacher training. Contains 26 references. (MSE)