Recent findings from social attention research suggest direct engagement with others is a necessary condition for the social cognitive development of both autistic children and their typically developing peers. These findings come from studies that have used eye-tracking technology and paradigms for measuring social attention in naturalistic, real-time settings. Social interactions allow two social partners to coordinate their attention in order to understand each other. Using a framework for studying social cognitive development and social attention in the context of social interactions, this article proposes the use of eye-tracking paradigms for social attention research and presents an intervention called "second-person interactions" (SPI). The article provides a review of eye-tracking research and interventions for social attention and describes the methods for assessing social attention using the SPI intervention.