This study evaluated whether the Family Bereavement Program (FBP), a prevention program for parentally bereaved families, improved parenting attitudes toward parental warmth and physical punishment in young adult offspring 15 years after participation and identified mediational cascade pathways. One hundred fifty-six parents and their 244 offspring participated. Data were collected at pretest (ages 8–16), posttest, and six- and 15-year follow-ups. Ethnicity of offspring was: 67% non-Hispanic Caucasian, 16% Hispanic, 7% African American, 3% Native American, 1% Asian or Pacific Islander, and 6% other; 54% were males. There was a direct effect of the FBP on attitudes toward physical punishment; offspring in the FBP had less favorable attitudes toward physical punishment. There were also indirect effects of the FBP on parenting attitudes. The results supported a cascade effects model in which intervention-induced improvements in parental warmth led to fewer externalizing problems in adolescence/emerging adulthood, which in turn led to less favorable attitudes toward physical punishment. In addition, intervention-induced improvements in parental warmth led to improvements in anxious romantic attachment in mid-to-late adolescence/emerging adulthood, which led to more favorable attitudes toward parental warmth in emerging/young adulthood. These findings suggest that the effects of relatively brief prevention programs may persist into subsequent generations.