  For an Anderson A-motive over a discretely valued field whose residue field
has A-characteristic \epsilon, we prove a criterion for good reduction in terms
of its associated local shtuka at \epsilon. This yields a criterion for good
reduction of Drinfeld modules. Our criterion is the function-field analog of
Grothendieck's and de Jong's criterion for good reduction of an abelian variety
over a discretely valued field with residue characteristic p in terms of its
associated p-divisible group.
