  Galileon gravity is a robust theoretical alternative to general relativity
with a cosmological constant for explaining cosmic acceleration, with
interesting properties such as having second order field equations and a shift
symmetry. While either its predictions for the cosmic expansion or growth
histories can approach standard \Lambda CDM, we demonstrate the incompatibility
of both doing so simultaneously. Already current observational constraints can
severely disfavor an entire class of Galileon gravity models that do not couple
directly to matter, ruling them out as an alternative to \Lambda CDM.
