This study used a single-case, multiple baseline design to examine the effectiveness of collaborative coaching on three Early Head Start (EHS) teachers' use of responsive communication strategies with toddlers with communication delays. Child communication targets and teacher communication strategies were measured as secondary outcomes. The coaching approach included a joint planning session in which the interventionist and teachers chose child targets and how to embed strategies within classroom routines. The teachers increased their use of the responsiveness strategies in play and caregiving routines during intervention and maintenance. Child participants also increased their rates of communication during intervention and maintenance. Implications for professional development and the social validity of the approach are discussed. (author abstract)