The purpose of the present study was to examine whether adolescent perceptions of mothers' and fathers' contributions to interparental discord changed from early to middle adolescence and if the changes were related to adolescent negative mood. Data were drawn from the National Longitudinal Survey of Youth 1997. Adolescents who were in 7th grade at the Wave 1 assessment and lived with both biological parents during Waves 1-4 were included in this research (n=812; 55% boys; 69% White). Findings indicated that adolescents' perceptions of their mothers' and their fathers' contributions to interparental discord increased at similar rates from early to middle adolescence. The largest increases in adolescent perceptions of mothers' and fathers' contributions to interparental discord from 7th to 9th grades were associated with the largest increases in adolescent negative mood from 7th to 10th grades. Girls' perceptions of their fathers' contributions to interparental relationship problems increased at a steeper rate compared with boys. Findings are discussed in the context of the sensitization hypothesis. (Contains 3 figures, 1 table and 1 footnote.)