It is now widely believed that classroom dialogue matters as regards student outcome, with optimal patterns often regarded as requiring some or all of: open questions; elaboration of previous contributions; reasoned discussion of competing viewpoints; linkage and coordination across contributions; meta-cognitive engagement with dialogue; high student participation. To date however, the relevance of such features has been most convincingly examined in relation to small-group interaction amongst students; little is known about applicability to teacher-student dialogue. The paper reports a large-scale study that permits some rebalancing. The study revolves around the two lessons (covering two of mathematics, literacy and science) that were video-recorded in each of 72 demographically diverse classrooms (students aged 10-11 years). Key measures of teacher-student dialogue were related to six indices of student outcome, which jointly covered curriculum mastery, reasoning, and educationally relevant attitudes. Prior attainment and attitudes were considered in analyses as were other factors, e.g. student demographics and further aspects of classroom practice, that might confound interpretation of dialogue-outcome relations. So long as students participated extensively, elaboration and querying of previous contributions were found to be positively associated with curriculum mastery, and elaboration was also positively associated with attitudes.