The birth of a preterm infant has been linked with parental distress and adjustment difficulties, yet little is known about the psychosocial factors contributing to this association. Using a cross-sectional design, we therefore examined maternal adjustment following preterm birth, with an emphasis on the potential role of experiential avoidance. We expected that high experiential avoidance, or unwillingness to experience private events (e.g., thoughts, emotions, bodily sensations), would mediate the relation between stress surrounding preterm birth and postdischarge adjustment difficulties. We further tested whether the association between experiential avoidance and maternal maladjustment was moderated or offset by high levels of child sociability or perceived social support. Sixty-six mothers with a preterm infant previously hospitalized in the Neonatal Intensive Care Unit (NICU) completed measures of NICU-related stress, experiential avoidance, postdischarge adjustment, perceived social support, and child temperament. As expected, experiential avoidance partially mediated the association between NICU-related stress and adjustment difficulties. Child sociability and perceived social support did not moderate the relation between experiential avoidance and adjustment, suggesting that high levels of experiential avoidance correlate with adverse outcomes irrespective of these variables. Some implications and recommendations for future research are discussed.