If black hole evolution respects quantum mechanics, it should be possible to describe it in terms of unitary evolution on a Hilbert space comprising subsystems. Since such evolution must apparently violate usual locality, we seek evolution laws that generalize those of quantum field theory. I will describe some modest attempts to characterize such evolution, in a maximally conservative fashion, guided by considerations of quantum information theory and other physical constraints. A broader framework is suggested, with localization replaced by tensor factorization of Hilbert space.