We report a new measurement of dijet production by color-singlet
exchange in ppbar collisions at sqrt s = 1.8 TeV at the Fermilab Tevatron.  In
a sample of events with two jets of transverse energy E^jet_T > 20 GeV,
pseudorapidity in the range 1.8 < |\eta^jet| < 3.5, and \eta_1 \eta_2 < 0, we
find that a fraction R = [1.13 +\- 0.12(stat) +\- 0.11(syst)]% has a
pseudrapidity gap within |\eta| < 1 between the jets that can be attributed to
color-singlet exchange.  The fraction R shows no significant dependence on
E^jet_t or on the pseudorapidity separation between the jets.