This article investigates the hypothesis that child labour is compelled by poverty. It shows that a testable implication of this hypothesis is that the wage elasticity of child labour supply is negative. Using a large household survey for rural Pakistan, labour supply models for boys and girls in wage work are estimated. Conditioning on non-labour income and a range of demographic variables, the article finds a negative wage elasticity for boys and an elasticity that is insignificantly different from zero for girls. Thus, while boys appear to work on account of poverty compulsions, the evidence for girls is ambiguous.