Links between brain function measures and quality of parent-child interactions within the early developmental period have been investigated in typical and atypical development. We examined such links in a group of 104 infants with and without a family history for autism in the first year of life. Our findings suggest robust associations between event related potential responses to eye gaze and observed parent-infant interaction measures. In both groups, infants with more positive affect exhibit stronger differentiation to gaze stimuli. This association was observed with the earlier P100 waveform component in the control group but with the later P400 component in infants at-risk. These exploratory findings are critical in paving the way for a better understanding of how infant laboratory measures may relate to overt behavior and how both can be combined in the context of predicting risk or clinical diagnosis in toddlerhood. [This article was written with members of the BASIS team: Simon Baron-Cohen, Rachael Bedford, Patrick Bolton, Susie Chandler, Janice Fernandes, Holly Garwood, Teodora Gliga, Kristelle Hudry, Greg Pasco, Evelyne Mercure, Leslie Tucker, and Agnes Volein.]