  We study the application of the background field method in the framework of
the exact renormalization group (ERG). By considering the case of a scalar
field theory, we provide a detailed discussion of the properties satisfied by a
background dependent Wilson action. We show how the Ward identity associated
with background field shifts for the Wilson action is related to that for the
1PI Wilson action, or effective average action. Moreover, we discuss the ERG
equations in the dimensionless framework and emphasize the role of the Ward
identity in this setting. We give two examples: the Gaussian fixed point for
the real scalar theory and the large $N$ limit of the linear sigma model.
