Purpose: During the 1970s, developmental psychology was concerned with the ability of individuals to adapt successfully despite the presence of significant stress or adversity. The focus was on identifying resources that help individuals adapt successfully, that is, protective factors. We examined the impact of parents' marital conflict and parent-adolescent conflict on adolescent depressive mood. In addition, we examined whether the protective factors of support from peers, professionals, and adults other than family members could moderate the effect of family conflict on adolescent depressive mood. We hypothesized that after controlling for gender and age, parents' marital conflict and parent-adolescent conflict were risk factors for adolescent depressive mood, but that support from peers, professionals, and other adults could be protective factors that reduced the effect of the aforementioned risk factors. Methods: Using stratified random sampling, 15 junior and senior high schools from 7 counties in Taiwan were selected for the study. A total of 1,416 students aged 12 to 19 from these schools participated. Data were compiled through self-report questionnaires administered in group settings. Hierarchical regressions with interaction effects were used to test the hypothesized models. Results: According to the results of the Center for Epidemiologic Study Scale-Depression (CES-D) scale, 83.3% of participants either did not suffer from a depressive mood or had a minor depressive mood, 16.0% were moderate, and 0.7% could be considered seriously depressive. The study revealed gender and age differences in depressive mood: females and older adolescents exhibited a greater degree. Hierarchical regression analyses indicated that female, older adolescents who had less peer support, more parental marital conflict, and more parent-adolescent conflict, tended to suffer a higher degree of depressive mood. Parent-adolescent conflict explained a relatively greater degree of variance in depressive mood. The moderating models were supported in four conditions. First, professional support had a protective-stabilizing effect on the relation of parents' marital conflict to adolescent depressive mood. When professional support was high, parents' marital conflict had no effect on adolescent depressive mood; however, the effect of marital conflict existed when there was a lack of professional support. Second, support from adults outside the family had a partially protective-stabilizing effect on the relation between parent-adolescent conflict and adolescent depressive mood. That is, support from adults outside the family could not completely eliminate the effect of parent-adolescent conflict, but it helped to reduce the impact of such conflict on adolescent depressive mood. Third, peer support had a protective-reactive effect on the relation of parents' marital conflict to adolescent depressive mood. That is, peer support could help adolescents adapt, but much more so when their parents' marital conflict was not very serious. Fourth, the same relationship was found in the effect of professional support on the relation of parent-adolescent conflict to adolescent depressive mood; it had the protective effect only when parent-adolescent conflict was not severe. Conclusions: On the basis of these findings, we suggested that concerned professionals should not only attempt to reduce parents’ marital and parent-adolescent conflict, but also provide support or utilize informal resources such as support from peers and other adults. Such support can help adolescents resist threats and stress from their families. We also provided new perspectives regarding the timing and techniques related to helping families in conflict.