Four grapevine training systems (single curtain, vertical shoot-positioned, high bush, and short bush) were compared for their effects on physiological performance, yield, vegetative growth, and must composition in Vitis vinifera L. cv. Tempranillo in Mediterranean weather conditions Net CO2 assimilation rate, stomatal conductance, and transpiration rate were measured at the beginning of bunch closure, veraison, and maturity on fully exposed leaves. At each stage, changes in these values were measured in the morning, at midday, and in the afternoon. Differences in individual leaf responses among treatments were the result of photosynthetically active radiation levels on the outer leaves. Fully exposed leaves of the bush-trained vines had the highest stomatal conductance and transpiration rates and those of the high-bush vines had the highest photosynthetic rates. Grape yield results showed that the vertical shoot-positioned system was the most productive, adjusted for its greater pruning level. Although acceptable grape quality was obtained with all four systems, single curtain and high bush had greater total soluble solids at the expense of lower grape yield. We recommend that you consult the full text of this article, which was originally published in the American Journal of Enology and Viticulture 56: 129-138.