  Let $f$ be a holomorphic mapping between compact complex manifolds. We give a
criterion for $f$ to have {\it unobstructed deformations}, i.e. for the local
moduli space of $f$ to be smooth: this says, roughly speaking, that the group
of infinitesimal deformations of $f$, when viewed as a functor, itself
satisfies a natural lifting property with respect to infinitesimal
deformations. This lifting property is satisfied e.g. whenever the group in
question admits a `topological' or Hodge-theoretic interpretation, and we give
a number of examples, mainly involving Calabi-Yau manifolds, where that is the
case.
