Although associations of attachment insecurity and sleep quality have gained major interest in recent literature, little attention has been given to dream content in this regard. The aim of this study was twofold: 1) to examine whether a relationship exists between attachment and the emotional tone of dreams (positive vs. negative); and 2) to investigate the potential mediator role of trait anxiety and depression between attachment and dream emotions. The sample consisted of 1661 university students (68.5% male; M age : 20.48 years). Attachment characteristics were assessed by the Relationship Scales Questionnaire, dream emotions were measured by the Dream Quality Questionnaire, while trait anxiety and depression were assessed using the Depression and Anxiety facets of the Revised NEO Personality Inventory. The results indicated that attachment anxiety and attachment style (secure, preoccupied, dismissing, and fearful) were associated with both negative and positive emotions in dreams even when controlling for sociodemographics and that these relationships were mainly mediated by general anxiety and depression proneness. However, attachment avoidance was not related with either dream quality indicator and dream recall frequency was unrelated with categorical attachment style. Major limitations of the study include the low ratio of females in the sample and the use of retrospective assessment methods in the measurement of dream content and dream recall frequency. Nevertheless, the results could provide new perspectives on the role of attachment in dreaming and might suggest that the consideration of attachment could help us better understand not only attachment-but nightmare-, mood-and anxiety disorders as well.