Gender differences in self-reported attachment styles of 18 individuals who had committed filicide were examined. Insecure attachment styles (avoidant and/or anxious-ambivalent) to primary caregivers were particularly common among males. Almost all experienced insecure romantic attachment. Partial support for insecure attachment continuity (childhood to adulthood), particularly among men, was found. Comparisons with 283 men and women who had committed other homicide types revealed that filicide males were the most common (across offender gender and victim-offender relationship) to hold insecure attachment to maternal caregivers. The role and nature of attachment patterns should be extended beyond the existing research focus on maternal filicide.