Eight major classroom observation studies correlating process variables (teaching techniques), and context variables (characteristics of school, curriculum, and student), with teaching effectiveness, (particularly achievement gains) were reviewed. This need to match process variables with context variables, rather than search for a universal teaching style was cited. One match has already been defined--traditional teachers in low socioeconomic classrooms appear to be consistently effective. Also, there is a strong subject matter/teaching style relationship in higher grades. Like the process variables, context variables--notably, classroom climate, teacher expectations, ability, socioeconomic status, mastery learning, and individualized instruction--generally have failed to correlate universally with achievement. Results of Canadian teacher effectiveness studies are similar; the most promising developments are taking place at Simon Fraser University, Memorial University and the University of Alberta. Current research is attempting to establish consistent generic relationships and to translate relationships into statements of cause and effect. Because this is necessarily a slow process, conclusions may be limited and tentative. Finally, the separation of educational research variables into school-based and non-school-based domains has considerable academic, political, and economic implications. (CP)