There is evidence of a long-term rise in the prevalence of adolescent emotional problems in the U.K. and in other countries. The aim of this study was to test whether time trends in parents' emotional difficulties contributed to these increases using data from two national surveys of English teenagers and parents studied twenty years apart (1986 and 2006). The 1986 sample is the age 16 follow-up of the 1970 British Cohort Study (N = 4524 adolescents, N = 7169 parents). The 2006 sample included 16/17-year-olds and their parents drawn from the 2002 and 2003 Health Surveys for England (N = 711). Both studies used identical self-complete questionnaire assessments of adolescent (GHQ-12 and Malaise Inventory) and parent (Malaise) symptoms of depression and anxiety. Follow-up data on emotional problems and psychiatric service use at age 30 years (N = 2785) for adolescents in the first cohort was used to validate the role of parent emotional problems as risk factors for offspring mental health. We found that maternal emotional problems increased across all socio-demographic groups between 1986 and 2006, mirroring increases in adolescent emotional problems over this period. They were cross-sectionally and prospectively associated with adolescent emotional problems. Cohort differences in adolescent emotional problems were attenuated when accounting for the increase in maternal emotional problems. Rising rates of maternal emotional problems have likely contributed to, but do not fully explain, recent time trends in adolescent emotional problems.