Two additional members of the High Risk Baby Siblings Research Consortium, Drs. Dawson and Rogers, have collaborated to develop a manualized intervention strategy that they have previously utilized for infants at risk of developing autism at an age as young as 12 months. This strategy is based on the Early Start Denver Model. The manual used in this strategy has a strong parent training focus, including a parent manual that emphasizes skills that promote affective engagement and social reciprocity. Preliminary results suggest that the Early Start Denver Model is effective for increasing language and cognitive ability in toddlers with autism. This project would utilize the adaptation of the Early Start Denver Model in two sites to symptomatic infants as young as 12-15 months of age, to study how this model compares to community-based-treatment “as usual” on social, affective and communication development as well as parental quality of life. Utilizing a parent-delivery model is most likely a more appropriate modality for very young infants and their mothers, and can be utilized for a wider range of parents and infants than a clinician-based strategy. Collaboration of these two investigators allows this intervention to be assessed in at least 60 “at risk” infants to be studied.