“This study is part of the NIH’s Helping to End Addiction Long-term (HEAL) initiative to speed scientific solutions to the national opioid public health crisis. The NIH HEAL Initiative bolsters research across NIH to improve treatment for opioid misuse and addiction.” Use of remote data collection methodology in developmental research has increased significantly, in part due to in-person data collection stoppage that occurred at the start of the COVID-19 pandemic. These kinds of data collection methods are likely to decrease barriers to participation for families, increase sample sociodemographic diversity, and could potentially address common problems in the field related to statistical power and sampling bias, all significant issues associated with construct and ecological validity. The central objective of this proposal is to support the rigorous application and validation of remote infant testing methodology of early cognitive development when infants are 4, 8, and 12-month of age. We will recruit 300 families who are traditionally underrepresented in developmental neuroscience research to participate in this longitudinal study. The primary aims of this project are to (i) establish and validate remote physiological and behavioral measurements of infant attention and memory skills, (ii) investigate the impact of caregiver-infant physiological co-regulation on infant outcomes, and (iii) evaluate predictors of infant attention phenotypes and longitudinal associations with socioemotional outcomes and autism risk. This proposal integrates multi-level data to improve measurement of infant cognition within the home and will substantially enrich our understanding of developmental trajectories and mechanisms across socio-demographically diverse environments and contexts, leading to increased precision for prevention and intervention efforts.