CONTEXT: Families are referred to pediatric palliative care (PPC) programs when a child is diagnosed with a medical condition associated with less than a full life expectancy. When a child dies, PPC programs typically offer a range of bereavement interventions to these families, often focusing on parents. Currently, it is unclear which factors increase the likelihood that bereaved siblings will experience negative outcomes, limiting the development of empirically supported interventions that can be delivered in PPC programs. OBJECTIVES: The present study explored the relationship between parents’ and surviving sibling’s mental health symptoms (i.e., post-traumatic stress disorder [PTSD], prolonged grief disorder (PGD), and depression symptoms) after a child’s death. Additionally, the extent to which parent functioning indirectly impacted sibling functioning through parenting behaviors (i.e., positive parenting and parent involvement) was also examined, with a specific focus on differences based on parent gender. METHODS: Sixty bereaved parents and siblings (aged 8-18) who enrolled in a PPC program from 2008 to 2013 completed measures of PTSD, PGD, and depression related to the loss of a child/sibling. Siblings also completed a measure of general parenting behaviors. RESULTS: Maternal, but not paternal, symptoms of PTSD and PGD were directly associated with sibling outcomes. Paternal symptoms were associated with sibling symptoms indirectly, through parenting behaviors (i.e., via decreasing positive parenting). CONCLUSION: These results underscore the importance of examining both maternal and paternal influences after the death of a child, demonstrate differential impact of maternal vs. paternal symptoms on siblings, and stress the importance of addressing postloss symptoms from a family systems perspective.