  The methods of effective field theory are used to study generic theories of
inflation with a single inflaton field. For scalar modes, the leading
corrections to the ${\cal R}$ correlation function are found to be purely of
the $k$-inflation type. For tensor modes the leading corrections to the
correlation function arise from terms in the action that are quadratic in the
curvature, including a parity-violating term that makes the propagation of
these modes depend on their helicity. These methods are also briefly applied to
non-generic theories of inflation with an extra shift symmetry, as in so-called
ghost inflation.
