Beginning in infancy, people can be characterized in terms of two dimensions of attachment insecurity: attachment anxiety (i.e., fear of rejection and abandonment) and attachment avoidance (distancing oneself from close others, shunning dependency; Bowlby, J., 1969/1982. Attachment and loss: Vol. 1. Attachment, 2nd ed., Basic Books, New York). The capacity for emotion regulation varies with attachment style, such that attachment-anxious individuals become highly emotional when threatened with social rejection or relationship loss, whereas avoidant individuals tend to distance themselves or disengage from emotional situations. In the present study, 20 women participated in an fMRI experiment in which they thought about--and were asked to stop thinking about--various relationship scenarios. When they thought about negative ones (conflict, breakup, death of partner), their level of attachment anxiety was positively correlated with activation in emotion-related areas of the brain (e.g., the anterior temporal pole, implicated in sadness) and inversely correlated with activation in a region associated with emotion regulation (orbitofrontal cortex). This suggests that anxious people react more strongly than non-anxious people to thoughts of loss while under-recruiting brain regions normally used to down-regulate negative emotions. Participants high on avoidance failed to show as much deactivation as less avoidant participants in two brain regions (subcallosal cingulate cortex; lateral prefrontal cortex). This suggests that the avoidant peoples' suppression was less complete or less efficient, in line with results from previous behavioral experiments. These are among the first findings to identify some of the neural processes underlying adult attachment orientations and emotion regulation.