The paper examines the linkages between child work hours and school performance of 11 391 children aged 5-17 years using Cameroon based on National Household Survey (ECAM 3, 2007). A bivariate probit model was used to select only those children who work and attend school. The endogeneity of hours of child labor has been corrected using the method of the
double least squares (2LS). The non linearity between school performance of children and work hours was taken into account through the inclusion square work hours and cube of work hours of children in the estimation. School performance of children was estimated using a Tobit model with double truncation. The main finding of econometric analysis is that, the first hours of child labor have a negative effect on school performance. The result suggest that a child can work up to somewhere between 13-34 hours a week without suffering a loss in her school performance.