PROJECT SUMMARY The SARS-CoV-2 (COVID-19) pandemic represents the most significant environmental event in living history. Sixty-eight million people worldwide have fallen ill to this disease, and 1.5 million people have died. Amongst those at greatest risk are society’s most vulnerable populations, including pregnant women and their children. It is unclear whether and how COVID-19 illness during pregnancy impacts the development of the child, as well as whether the timing of illness has any influence over this effect. It is also unknown whether environmental factors may mitigate observed outcomes. The present study will examine neurobehavioral trajectories in 100 children, half of whom will be born to women with COVID-19 infection diagnoses during pregnancy. Infants will undergo prospective longitudinal assessments at 1-, 6-, 9- and 12-months, including MRI 1 month (N = 50) and 12 months (N = 100). Our central hypotheses are that (1) perinatal COVID-19 leads to differences in infant attention, affect, myelination, and systems-level neural functional connectivity and that (2) earlier timing of prenatal infection and illness severity increase risk for developmental delay. We will explore specific environmental factors with potential influence over the association between maternal prenatal COVID-19 infection and child outcomes, particularly pre- and postnatal psychological health and partner support. We will thus be able to meaningfully evaluate whether, and how, prenatal COVID-19 illness modifies neurobehavioral development of infants and will address how variation in maternal psychobiological health influences observed associations.