Research on neighbourhood effects indicates that neighbourhood poverty is related to educational outcomes of youth, however, much less attention is spend on studying neighbourhood and school effects simultaneously. Because the demographic composition of both contexts likely overlaps to some extent, it is possible that the effect both contexts have is not independent of each other. Throughout the early teenage years the neighbourhood and school contexts can vary, advocating for a life-course approach, including how the timing and duration of exposure to either contexts affect educational achievement. Using the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort (N=4,502), we employed cross-classified multilevel models to examine the timing and duration of exposure to poverty in neighbourhood and school contexts between ages 10 and 16, to predict educational achievement of adolescents at age 16. Our results indicate that neighbourhood poverty impacts on educational achievement, independent of school poverty. Furthermore, we found that for neighbourhood poverty, especially enduring exposure impacts on educational achievement, while the timing of exposure does not play a role. However, for school poverty, both timing and duration play a role: longer exposure is related to lower achievement, but also exposure at an earlier age has a stronger impact than exposure at a later age. Finally, the lowest educational achievement was observed in adolescents who were exposed to poverty in both contexts for the full observation period. In sum, our analyses indicate that, when studying contextual disadvantage, it is crucial to consider how variations over time in different contexts might be related and how they might influence the study.