Models of differential susceptibility hypothesize that neural function may be a marker of differential susceptibility to context, but no studies have tested this hypothesis. Using a sample of 310 young men from low-income urban neighborhoods, this study investigated amygdala reactivity to facial expressions as a moderator of the relations between socioeconomic resources and later antisocial behavior (AB) and income. For individuals with high amygdala reactivity, greater socioeconomic resources at age 20 predicted less AB and greater income at age 22. For young men with low amygdala reactivity, however, socioeconomic resources at age 20 did not predict later outcomes. Amygdala reactivity to fearful facial expressions, key to the etiology of AB, moderated links between resources and AB. In contrast, amygdala reactivity more generally to multiple facial expressions moderated the effects of resources on later income attainment. Both interactions met rigorous quantitative criteria for patterns of differential susceptibility rather than diathesis stress or vantage sensitivity. Moreover, these associations remained significant after inclusion of socioeconomic resources during earlier developmental periods. These results suggest that greater amygdala reactivity to facial expressions is a marker of greater susceptibility to context, for better or for worse, during the transition to adulthood.