Early life adversity impacts more than half of youth worldwide and is thought to contribute to a third of adult mental illness. In particular, early caregiving adversity (ECA) – including exposure to abuse, neglect, or circumstances surrounding placement in institutional or foster care – has profound consequences for socioemotional, cognitive, and behavioral development, and is a potent contributor to later psychopathology. While ECA research has focused on high-level cognitive and socioemotional capabilities crucial to preventing psychopathology, preliminary work in children suggests that ECA may also elevate risk for lower-level sensory processing challenges. Across three multi-method studies, this dissertation introduces consistent evidence that diverse forms of severe early caregiving adversity increase risk for sensory processing challenges that persist beyond early childhood into adolescence and young adulthood, and furthermore suggests that these sensory symptoms may contribute to the development of mental health challenges across populations. Study 1 found that two rare but profound categories of ECA are associated with elevated parent-reported sensory processing challenges in children and adolescents, and that these in turn are linked to elevated internalizing and externalizing symptoms. Study 2 showed that self-reported adversity-linked sensory challenges (and the same accompanying associations with internalizing symptoms) are present following experiences of more prevalent forms of ECA (e.g., neglect, abuse), persisting into adulthood. In addition, this study evaluated three candidate neurodevelopmental mechanisms that may contribute to the emergence of these sensory processing challenges, indicating affective and regulatory processes may be particularly important to consider in the context of enduring sensory symptoms. Lastly, Study 3 extended these findings, reporting elevated recruitment of prefrontal regulatory regions during aversive sensory stimulation in youth with histories of caregiving institutionalization, and providing novel evidence for the importance of regulatory experiences in the development and persistence of sensory processing challenges following ECA. Taken together, these studies advance developmental models of ECA by pointing to the importance of sensory processing as an underexplored and potentially tractable facet of development that may be critical to long-term mental health.