  The nonleptonic weak $|\Delta S|=1$ $\Lambda N$ interaction, responsible for
the dominant nonmesonic decay of all but the lightest hypernuclei, is studied
in the framework of an effective field theory. The long-range physics is
described through tree-level exchange of the SU(3) Goldstone bosons, while the
short-range potential is parametrized in terms of the lowest-order contact
terms. We obtain reasonable fits to available weak hypernuclear decay rates and
quote the values for the parity-violating asymmetry as predicted by the present
effective field theory.
