When members of a classroom community routinely listen to one another and build on one another's ideas, not only do students learn and improve their cognitive and communication skills, but teacher and students develop a disposition to listen, think and talk together. However, such dialogic, classroom talk is rare. In this study we show how a teacher's epistemological commitment (that student ideas matter) combined with oracy practices (safe space for student talk; student ideas drive classroom talk; support multiple perspectives) realized through speculation and reasoning (S&R) words foster dialogic talk. We examined S&R words (think, would, might/maybe, if, so, but, how, why) in 1299 turns of talk in two lessons in one classroom of six 4–5th grade English Language Learners. Statistical discourse analysis showed that S&R words occurred more often during what we refer to as connect episodes (students made personal connections to the content), not after particular types of turns. Close discourse analysis showed how S&R word use cultivated a language of possibility and how management of classroom discourse modality promoted dialogic talk. Copyright © 2019 Elsevier Inc. All rights reserved.