  Based on an effective field theory of hadrons in which quantum chromodynamics
is assumed to provide the necessary bare cutoff functions, a gauge-invariant
theory of pion photoproduction with fully dressed nucleons is described. The
formalism provides consistent dynamical descriptions of pi-N --> pi-N
scattering and Gamma-N --> pi-N production mechanisms in terms of nonlinear
integral equations for fully dressed hadrons. The dressed hadron currents and
the pion photoproduction current satisfy gauge invariance in a self-consistent
manner. Approximations are discussed that make the nonlinear formalism
manageable in practice and yet preserve gauge invariance.
