Objectives: This article reports on results from a randomized experimental trial of the effects of the Family Bereavement Program (FBP) on multiple measures of grief experienced by parentally bereaved children and adolescents over a 6-year period. Method: Participants were 244 youths (ages 8-16, mean age = 11.4 years) from 156 families that had experienced the death of a parent. The sample consisted of 53% boys and 47% girls; ethnicity was 67% non-Hispanic White and 33% ethnic minority. Families were randomly assigned to the FBP (N = 135) or a literature control condition (N = 109). Two grief measures, the Texas Revised Inventory of Grief and the Intrusive Grief Thoughts Scale (IGTS) were administered at 4 times over 6 years: pretest, posttest, and 11-month and 6-year follow-ups. A 3rd measure, an adaptation of the Inventory of Traumatic Grief (ITG) was administered only at the 6-year follow-up. Results: Compared with the control group, the FBP group showed a greater reduction in their level of problematic grief (IGTS) at posttest and 6-year follow-up and in the percentage at clinical levels of problematic grief at the posttest. The FBP also reduced scores on a dimension of the ITG, Social Detachment/Insecurity, at 6-year follow-up for 3 subgroups: those who experienced lower levels of grief at program entry, older youths, and boys. Conclusion: These are the first findings from a randomized trial with long-term follow-up of the effects of a program to reduce problematic levels of grief of parentally bereaved youths. (Contains 3 tables, 1 figure and 6 footnotes.)