If photorespiration could be reduced in current C3 crops, or if they could be converted to use C4 photosynthesis, large economic and environmental benefits would ensue because of both their increased productivity and the reduced inputs per unit yield associated with the C4 pathway. It is important to note that the huge advances in agricultural production associated with the Green Revolution were not associated with increases in photosynthesis, and sot its manipulation remains an unexplored target for crop improvement both for food and biomass. Even partial long-term success would have significant economic and environmental benefits. Efficient C4 photosynthesis is associated with alterations to leaf development, cell biology and biochemistry and so transferring these traits into C3 crops is a long-term undertaking. Despite its complexity, C4 photosynthesis has evolved independently at least forty-five times and this argues strongly for it being a tractable system to understand. We will undertake fundamental research to uncover mechanisms underlying important aspects of the C4 leaf that so far have remained undefined. In the medium term, this will allow these important C4 traits to be transferred into C3 crops. In addition, to compliment this long-term work, we will also increase photosynthesis by introducing a synaptic bypass for photorespiration into European crops. We will also build capacity for C4 research in Europe through the training of future generations of researchers.