The δ13C values of soil organic matter record information regarding the relative importance of C3 versus C4 plants in past plant communities. Because the geographical distribution of C4 plants is correlated strongly with temperature, δ13C of soil organic matter has the potential to enhance understanding of climate history. The purpose of the paper was to: (1) demonstrate that δ13C of soil organic matter responds to and records changes in the relative abundances of C3 and C4 plants in situations where plant community histories are well known; then (2) apply this technique to soil organic matter in palaeosols representing the past 15 000 years in order to reconstruct vegetation and climate change during that period. The δ13C values of soil organic matter accurately documented vegetation dynamics at two sites where land use and vegetation history had been quantified previously: a tallgrass prairie and a subtropical woodland. Changes in δ13C values of organic matter in palaeosols from central Texas indicated shifts in the relative abundance of C3 and C4 plants which tracked changes in climate indicated from accounts published previously and based on other climate reconstruction techniques. Results indicate that δ13C of soil organic matter, by reflecting the relative contribution of C3 and C4 species to plant community productivity, can be used to reconstruct vegetation history and can therefore serve as a proxy indicator of past climate.