Abstract
Child labour can deprive children of the right to a normal childhood and impair their productivity and earning capacity in later life. The relationship between child labour and cognitive development is central to these effects but has not yet been a focus of empirical research. Using panel data from Ethiopia and applying an instrumental variables estimator, we find a strong association of cognitive development with the amount of time previously spent by children on income-generating work, and with the amount of time spent on household chores. Existing levels of child labour in Ethiopia are thus demonstrably harmful.