How do subject specialists construe classroom language proficiency?

Recent research on rater variation (e.g., Barnwell, 1989; Douglas and Selinker, 1990; Hadden, 1991) raises the question of whether 'linguistically naive' subject specialists may be better equipped than language experts to judge the effectiveness of particular areas of non-native speaker communica tion. This question is investigated with reference to a classroom-based observation schedule which was developed to assess the English language proficiency of non-native speaker graduates training as secondary mathema tics and science teachers. The article examines aspects of rater behaviour as evidenced in recent trials. The schedule was applied to observations of actual performance in the maths and science classroom as well as to the viewing of a number of videoed segments of classroom interaction. Ratings were elicited from two groups of assessors: nine ESL teachers and eight subject specialists (maths/science teachers/teacher trainers). Findings reveal significant correlations between subject specialists' and language teachers' overall judgements of communica tive effectiveness, but differences between the two groups with respect to their ratings of particular dimensions of language use and to the weighing of these dimensions in relation to global proficiency assessments.