  We propose an extension of tri-bimaximal mixing to include a non-zero reactor
angle $\theta_{13}$ while maintaining the tri-bimaximal predictions for the
atmospheric angle $\theta_{23}=45^o$ and solar angle $\theta_{12}=35^o$. We
show how such tri-bimaximal-reactor mixing can arise at leading order from
the(type I) see-saw mechanism with partially constrained sequential dominance.
Partially constrained sequential dominance can be realized in GUT models with a
non-Abelian discrete family symmetry, such as $A_4$, spontaneously broken by
flavons with a particular vacuum alignment.
