It has long been recognized that photosynthesis and respiration in the plant cell must be intimately linked, given that they share carbon dioxide and oxygen as substrate and product or as product and substrate, respectively (for review, see Siedow and Day, 2000). While the core reaction schemes of the pathways of photosynthesis, respiration, and the associated process of photorespiration are well defined, it is only since the advent and widespread adoption of reverse genetic strategies that the high level of interaction between them has begun to be fully realized (Bauwe et al., 2010; Sweetlove et al., 2010). However, the exact contribution of each pathway to energy status is dependent on cell type, and fundamental questions such as the degree of inhibition of the tricarboxylic acid (TCA) cycle in the light remain somewhat controversial. Here, we will outline current understanding of the influence of mitochondrial function, focusing almost exclusively on the illuminated leaf of C3 plants and taking the majority of our case studies from tomato (Solanum lycopersicum) and Arabidopsis (Arabidopsis thaliana). We contend that, having achieved a more comprehensive understanding of the interaction between photosynthesis and respiration (and indeed also photorespiration), the manipulation of mitochondrial metabolism and machinery has recently emerged as a novel potential means to enhance photosynthesis.