Journal article: This article uses time-use and household expenditure data to measure the substitutability between time and money within the Beckerian household production framework. The elasticity of substitution is estimated for five commodity groups and across two developing countries: Ecuador and Guatemala. The estimated elasticities are positive, indicating substitutability, and much larger for all other goods compared to food. Our results raise some interesting questions regarding the policy effects of an intervention that does not consider the money/time trade-offs in consumption.