  We investigate the Goos-H\"{a}nchen (GH) shifts of partially coherent fields
(PCFs) by using the theory of coherence. We derive a formal expression for the
GH shifts of PCFs in terms of Mercer's expansion, and then clearly demonstrate
the dependence of the GH shift of each mode of PCFs on spatial coherence and
beam width. We discuss the effect of spatial coherence on the resultant GH
shifts, especially for the cases near the critical angles, such as totally
reflection angle.
