Attachment theory has played an important role in attempts to understand the “cycle of violence,” where maltreated children are at increased risk for perpetrating violence later in life. However, little is known empirically about whether adult attachment insecurity in close relationships may partly explain the link between childhood maltreatment and violent behavior. This study aimed to address this gap using data from a prospective longitudinal study of documented childhood abuse and neglect cases and demographically matched controls (ages 0–11 years), who were followed into adulthood and interviewed (N = 892). Participants completed the Relationship Scales Questionnaire assessing adult attachment styles at mean age 39.54. Criminal arrest data were used to determine arrests for violence after the assessment of attachment through mean age 50.54. There were significant direct paths from childhood maltreatment and adult attachment insecurity to violent arrests after attachment measurement. Attachment insecurity partly explained the higher levels of violence in individuals with maltreatment histories. Analyses of maltreatment subtypes and attachment styles revealed that attachment anxiety appeared to mediate paths between neglect and physical abuse and later violence. There were no significant indirect paths from neglect or physical abuse to violence via attachment avoidance. Implications and future directions are discussed.