Stay-at-home orders and social distancing measures during the COVID-19 pandemic have been associated with increased stress, changes in youths’ routines, and greater uncertainty within the family system. There is evidence that the pandemic has led to changes in adolescent symptomatology, although heterogeneity in findings suggests that other factors may also play a role. We examined how family-level stressors were associated with parent- and youth-reported youth anxiety and depressive symptoms six months later during the first year of the pandemic. Data were collected from 259 youth (Mage = 15.38, SD = 1.65) and their families in Pennsylvania and the surrounding region from August 2020 to May 2021. Anxiety and depression presented differential patterns in response to COVID-19. We observed strong stability in parent-reported symptoms across this period, and moderate stability in youth reports of their depressive symptoms. Parent-reported COVID-19 pandemic impact on the family (e.g., job changes) was positively associated with parent reports of youth anxiety both concurrently and six months later, but not with parent reports of youth depressive symptoms. Controlling for the financial, health, and social impact of the COVID-19 pandemic on the family, youth-reported household chaos was positively associated with parent reports of youth depressive symptoms six months later. Youth reports of family conflict concerns were positively associated with their self-reported anxiety and depressive symptoms six months later. These results highlight the importance of considering the family system in understanding differences in adolescent anxiety and depressive symptoms during broader geopolitical stressful life events.