  We present a microscopic model for coherent pion production off nuclei
induced by neutrinos. This model is built upon a model for single nucleon
processes that goes beyond the usual Delta dominance by including non resonant
background contributions. We include nuclear medium effects: medium corrections
to Delta$ properties and outgoing pion absortion via an optical potential. This
results in major modifications to cross sections for low energy experiments
when compared with phenomenological models like Rein-Sehgal's.
