This paper presents different substitution mechanisms which determine, in a theoretical framework, the conditions for long-term sustainable development. In a one-sector approach and in two versions of a multi-sector endogenous growth model, the accumulation and the substitution of man-made inputs for natural resources are analysed. Assuming man-made capital to be an output of a specific sector of the economy, the elasticities of substitution between the different inputs play a more complex role than suggested by the one-sector approach. According to the multi-sector models, the prediction of growth becoming sustainable emerges as realistic, provided that the sectoral adjustment costs in the economy are not too high.