This paper evaluates the causal effect of the Child Support Grant (CSG) implemented in South Africa on household food consumption and dietary diversity. The analysis uses the National Income Dynamics Study (NIDS) covering 2008, 2010-2011 and 2012, and carries out a regression discontinuity design exploiting the increase in the age limit criteria for eligibility for the program. Our results show that the CSG have proved to be effective in increasing total food expenditure per adult equivalent but has not significantly changed the dietary habits of the beneficiary households, nor has the program resulted in any stronger effect for the most vulnerable subgroups of the beneficiary population. To analyse the external and internal validities of the results, a comparison between non-parametric, semi-parametric and parametric estimates is presented.