Children's learning and cognitive development have a distinct receptivity to the circumstances of childhood. However, not all children have equal opportunities and learning inequities continue to be influenced by the social and economic circumstances of childhood. Examining factors within the environments that children are growing up in, and the associations of these factors with learning, can help to identify leverage points for change, enabling more children to be supported to reach their potential. Specifically, turning attention to the timing and duration of exposure to specific social and economic factors across childhood can provide essential details to determine who is most susceptible to contextual effects and at what ages. This paper presents a systematic review of 75 longitudinal studies of families and children carried out between 2000 and 2021. These studies tracked social and economic circumstances between pregnancy and early adolescence in relation to educational and cognitive outcomes across the lifespan. The results of the included studies were examined and grouped into themes using reflexive thematic analysis. The findings largely suggest that the degree to which educational and cognitive outcomes are affected by specific social and economic circumstances depends on the duration, timing, and mobility across childhood. In particular, findings relating to the developmental timing of exposure, as well as persistent exposure, revealed distinct evidence of the effects of temporality. These findings provide detail into how much and in what instances temporality should be considered--results which can be used to inform avenues for reducing learning disparities.