<p>The current study explored whether youths’ parasympathetic functioning (indexed by respiratory sinus arrhythmia reactivity; RSA reactivity) moderates the associations between adverse childhood experiences (indexed by childhood abuse/neglect) and depressive symptoms. A total of 97 Chinese undergraduates (27.8% males, 72.2% females; <i>M</i>_<i>age</i> = 19.09 years, <i>SD</i> = 0.91) participated in this study. Participants completed a short version of the Child Trauma Questionnaire and Beck Depression Inventory to assess childhood abuse and neglect, as well as depressive symptoms. Subsequently, they performed a mental arithmetic task during which physiological data was collected. Results indicated that RSA reactivity during the mental arithmetic task moderated the positive relations of childhood abuse and neglect to symptoms of depression, respectively. Higher levels of childhood abuse or neglect are associated with higher levels of depression only among adults with low and average RSA reactivity, but not high. This study provides novel evidence that the extent to which childhood adversities place youths at increased risk for depression depends on youths’ parasympathetic functioning. Greater physiological regulation abilities (indexed by greater RSA reactivity) may act as a protective factor against the adverse effects of childhood abuse/neglect on depressive symptoms.</p>