  The recently-discovered narrow charmonium resonance near 3870 MeV is
interpreted as a hadronic molecule whose constituents are the charm mesons D^0
and \bar D^{*0} or \bar D^0 and D^{*0}. Because of an accidental fine-tuning of
the molecule to very near the D^0 \bar D^{*0} threshold, it has some universal
properties that are completely determined by the unnaturally large D^0 \bar
D^{*0} scattering length a. Its narrow width can be explained by the
suppression by a factor of 1/a of decay modes other than the decay of a
constituent \bar D^{*0} or D^{*0}. Its production rates are also suppressed by
a factor of 1/a. A particularly predictive mechanism for generating the large
scattering length is the accidental fine-tuning of a P-wave charmonium state to
the D^0 \bar D^{*0} threshold.
