  The present status of the theoretical description of electromagnetic
reactions on the deuteron above pion threshold is reviewed. Three major topics
are considered: (i) retardation effects in $\pi$-meson exchange contributions
to $NN$-interaction and meson exchange currents in deuteron photodisintegration
above $\pi$-threshold in the $\Delta$-resonance region, (ii) off-shell effects
in the one-body current treated in a simple pion cloud model in deuteron
photodisintegration in and above the $\Delta$-resonance region, and (iii) final
state interaction effects in photoproduction of $\pi$ and $\eta$ mesons on the
deuteron.
