  We show that the spontaneous scalarization scenario in scalar-tensor theories
is a specific case of a more general phenomenon. The key fact is that the
instability causing the spontaneous growth in scalars is due to the nonminimal
coupling in the theory, and not related to the nature of the scalar. Another
field with the same form of coupling undergoes spontaneous growth as well. We
explicitly demonstrate this idea for vectors, naming it "spontaneous
vectorization", and study spherically symmetric neutron stars in such a theory.
We also comment on other tensor fields the idea can be applied, naming the
general mechanism "spontaneous tensorization".
