Homicides involving biological parents were analyzed separately from those involving stepparents. In the initial screening of the data set, cases involving obvious coding errors were excluded from further analysis. Findings revealed that these cases are rare. A total of 79 fathers, 40 mothers, 47 stepfathers, and 14 stepmothers were killed by more than one offender. Of these, at least 1 juvenile was involved in the killings of 45 fathers, 19 mothers, 14 stepfathers, and 1 stepmother. Situations in which a single juvenile killed more than one victim, including one parent, also appeared to be rare. Sixty-two fathers, 111 mothers, 9 stepfathers, and 13 stepmothers were killed in multiple- victim, single-offender situations. However, these numbers underestimate the actual numbers of parents killed by their children in situations of this type. Findings indicated that, at most, 10 family mass murders were perpetrated by juveniles during the 10-year period and that the killing of entire families by sons and daughters under 18 is clearly not a significant problem in the United States. Results also suggested that the FBI needs to change its data collection procedures to permit more precise analyses. Tables, notes, and 24 references