  I show how to compute the exact one-loop thermal correction to the free
energy of a soliton. The method uses the effective potential as an auxiliary
step to ensure that the soliton is quantized around the appropriate vacuum. The
exact result is then computed using scattering theory techniques, and includes
all orders in the derivative expansion. It can be efficiently combined with a
calculation of the exact quantum correction to yield the full free energy to
one loop. I demonstrate this technique with explicit computations in $\phi^4$
models, obtaining the free energy for a kink in 1+1 dimensions and a domain
wall in 2+1 dimensions.
