Intercropping is the cultivation of two or more crop species simultaneously in the same field. Intercropping is widely practiced by smallholder farmers in developing countries and is gaining increasing interest in developed countries to increase agricultural yields per unit land. Yield increase in intercropping is best captured by the land equivalent ratio: the land area required when using sole crops to achieve the same yields as obtained on a unit area of intercrop. In this thesis, I use meta-analysis and functional structural plant modelling to determine how the land equivalent ratio of intercrops is influenced by plant traits (e.g. N-fixation ability or C3 versus C4 photosynthesis) and spatio-temporal configuration of species. I demonstrate the key importance of temporal niche differentiation. The findings support the notion that intercropping can help to meet the demand for food, feed, fuel and fiber while mitigating the environmental impacts of modern agriculture.