Our research indicates that the temperature sensitivity of soil organic matter (OM) decomposition increases with decreasing soil OM lability. Thus, as temperature increases the rate of decomposition also increases due to metabolism of more recalcitrant organic matter rather than by increasing the decomposition rate of labile material. An important corollary hypothesis is that the abundance of microbes able to decompose more recalcitrant organic matter increases with increasing temperature. To test this hypothesis, we incubated soils at 5, 15 or 25 ºC for 150 days and then raised the temperature 10 ºC, assessing microbial community composition before and 30 days after the temperature bump. We found consistent changes in the lipid profiles of the soil microbial community in response to temperature despite differing community structure among the soils. Although this in part may signal a membrane response within individual cells, it most likely represents a community shift due to the large number of fatty acids included in the discriminant model. Results from this research will provide insight into soil organic matter stability under pressures from global warming. Furthermore, it will direct future research on microbial adaptations to global temperature change.