Preliminary efforts to operationalize more fully the concept of the instructional conversation (IC) approach for second language learning are reported, and an observational tool, the IC Rating Scale, is described in an examination of classroom-based reading comprehension lessons. Preliminary data on the reliability and validity of the IC scale are presented, followed by sample transcripts of instructional conversations from actual reading comprehension lessons. Cautions and unresolved questions to be considered in using the scale are discussed, including: (1) although the IC scale is composed of a series of distinct elements, the unit of analysis must be the whole lesson and the interactional context in which the lesson activities are situated; (2) the elements do not represent steps or other top-down, teacher-proof prescriptions, but instead are components that characterize and contribute to the types of activity settings; and (3) the scale should not be seen as a finished product. Suggestions for future research are noted. Appendices describe the elements of instructional conversation and provide both the scoring sheet and the summary score sheet. Contains 13 references. (LB)