This prospective, longitudinal study explored the relationship between mothers unresolved/disorganized (U/d) attachment status and frightened/frightening (FR) maternal behavior and investigated possible variations due to whether mothers were U/d for loss versus abuse. The role of other factors that might predict maternal FR behavior was also examined. Pregnant women (n = 116) were administered the Adult Attachment Interview and later observed at home for 30-40 min interacting with their first-born 8-month-olds. Women classified as U/d with respect to loss and/or abuse displayed substantially higher levels of FR behavior with their infants than did mothers who were not classified as U/d (i.e., secure/autonomous, dismissing, or preoccupied), but these groups did not differ on maternal sensitivity. Mothers classified as U/d who had a secondary secure/autonomous classification also showed FR behavior but at low levels than U/d-insecure mothers. Independent of U/d status, mothers who had lost a parent, versus those who did not, more often displayed FR behavior with their infants. Finally, U/d loss fully mediated the association between loss of an attachment figure other than the parent and FR behavior, and partially mediated the relationship between loss of a parent and FR behavior.