  We develop the point of view that brane actions should be understood in the
context of effective field theory, and that this is the correct way to treat
classical as well as loop divergences. We illustrate this idea in a simple
model. We then consider the implications for the dynamics of antibranes in flux
backgrounds, focusing on the simplest case of a single antibrane. We argue that
there is no tachyonic instability at zero temperature, but there is a
nonperturbative process in which an antibrane annihilates with its screening
cloud. This is distinct from the NS5-brane instanton decay. Constraints on
models of metastable supersymmetry breaking by antibranes may be tightened, but
there is no problem of principle with this mechanism.
