Our preliminary research using randomized experimental designs has tested the effects of the intervention when delivered in a very small 'dose', averaging just over one hour per week for six months. This standard dose has led to significant but modest effects in the children's use of intentional communication and early language, such that it could be adopted by speech-language pathologists as part of standard care. Unfortunately, the early benefits have not always been maintained 6 and 12 months after the therapy phase ends and have not always benefitted all children.