  The radiative capture process n+p-> d+gamma provides clear evidence for meson
exchange currents in nuclear physics. We compute this process at low energies
using a recently developed power counting for the effective field theory that
describes nucleon-nucleon interactions. The leading order contribution to this
process comes from the photon coupling to the nucleon magnetic moments. At
subleading order there are other contributions. Among these are graphs where
the photon couples directly to pions, i.e. meson exchange currents. These
diagrams are divergent and require the presence of a local four-nucleon-one
photon counterterm. The coefficient of this operator is determined by the
measured cross section, 334.2 +- 0.5 mb, for incident neutrons with speed
|v|=2200 m/s.
