Technical Abstract: Plants experience fluctuating light and temperature, and species' acclimation defines both their ecological niches and optimal growth ranges. Interactions between light and temperature may be evident because of covariance of photosynthesis and respiration with these parameters. It is, therefore, important to determine the effect of a change in light and temperature on respiration and carbon use efficiency both separately and together. Separating respiration into growth and maintenance components and tissue analysis revealed that carbon use efficiency has the capacity to acclimate to changes in light through a reduction in the maintenance coefficient, an increase in the growth coefficient, and relatively less partitioning of N in protein. Temperature had no significant effect in determining either maintenance or growth coefficients. These data suggest that carbon use efficiency can be maintained at a high level provided carbohydrate supply can meet respiratory demand, even in low light.