BACKGROUND Fostering, raising children that are not one's biological children, is common in many societies worldwide. Despite predicted lower investment in nonbiological offspring, numerous studies report no obvious well-being penalty for fostered children. Building on prior research, we suggest that fostering is incentivised by close relatedness between foster child and caregivers and that children's work contributions can offset their costs to fostering households. METHOD We used multilevel logistic and fractional multinomial regression analyses to investigate the association between fostering, educational investment, and time allocation in a sample of 1,273 Sukuma children (aged 7-19) from northwestern Tanzania, where fostering is traditionally common. RESULTS Twenty-six per cent of children are fostered, with most having at least one living parent. Children fostered by close kin have similar educational outcomes to those living with both biological parents, though their grade for age is lower, perhaps reflecting differences in timing rather than overall level of investment. Those fostered by distant kin are less likely to be enrolled or to progress to secondary school. Overall, fostered children are more likely to do farm work; however on weekdays when work conflicts with school, differences in time allocation to work activities are not pronounced. We further find that orphans are generally not particularly disadvantaged compared to other fostered children. CONCLUSION Being fostered by close kin does not appear to disadvantage children, and buffers orphans from parental death. Fostered children may offset some of their costs through increased farm work. CONTRIBUTION We extend previous work in this area through analysis of detailed time allocation data, providing insights into associations between fostering and children's workload.