This panel highlights the multiple uses of eye tracking, from investigations of mechanisms, towards tools of clinical value. The first presentation (n=234) presents on brief, scalable, gaze-contingent eye tracking batteries that tap into social motivational processes and segregate children with and without ASD. The second (n=100) deconstructs factors underlying diminished face looking in toddlers with ASD, highlighting decreased attention to the mouth in ASD in response to speech and its relationship to autism symptoms. The third (n=129) uses a novel gaze-contingent value learning task to examine contribution of value learning to atypical selective social attention in toddlers with ASD, highlighting the potential disruption in the reward system network involved in value learning and signaling value-based attentional priorities during early stages of the disorder. The fourth (n=201) advances scalable eye-tracking-based measures designed specifically for clinical application in ASD, highlighting their strong psychometric properties and links with language ability. Together, these studies cut across the lifespan, inform our understanding of the earliest manifestations of ASD, employ some of the latest paradigms and technologies in both autism and eye-tracking research, help to isolate developmental and cognitive constructs, and bring us closer towards a future of eye tracking as a clinical tool.