Although triangulation into parental conflict is a risk factor for child and adolescent maladjustment, little is known about how triangulation affects adolescents' functioning or the factors that lead children to be drawn into parental disagreements. This prospective study examined the relations between triangulation, appraisals of conflict, and parent-child relations in a sample of 171 adolescents, ages 14 to 19 years, at 2 time points. Cross-lagged path analyses revealed that youths who experienced greater threat in response to conflict reported increases in triangulation over time, and triangulation was associated with increased self-blame and diminished parent-adolescent relations. This study highlights links between intrapersonal, dyadic, and triadic processes and suggests a mechanism by which interparental discord spills over into parent-adolescent relations.