Impulsivity, specifically negative urgency, is associated with diverse health risk behaviours, yet relatively little research has examined factors contributing to negative urgency. The purpose of this study was to examine the relationship between childhood maltreatment, alexithymia and negative urgency. The sample was comprised of 410 undergraduate students who completed measures online. A series of regression analyses tested whether alexithymia mediated the association between childhood maltreatment and negative urgency. Results supported the hypothesized mediation model. Subsequent analyses examined effects of specific subtypes of maltreatment and alexithymia subscales. These analyses indicated that growing up in a punishing environment (e.g. being hit or beat; expected to follow a strict code of behaviour) was indirectly associated with negative urgency via difficulty identifying feelings, suggesting that excessive use of punishment during childhood may reduce the development of the ability to identify and label feeling states. This difficulty in emotional processing may in turn lead to acting rashly when emotionally aroused. Copyright (c) 2013 John Wiley & Sons, Ltd.