We report a measurement of the fraction of dijet events with a rapidity gap
between jets produced by color-singlet exchange in (p) over bar p collisio
ns at root s = 630 GeV at the Fermilab Tevatron. In events with two jets of
transverse energy E-T(jet) > 8 GeV, pseudorapidity in the range 1.8 < \n(j
et)\ < 3.5 and eta(1)eta(2) < 0, the color-singlet exchange fraction is fou
nd to be R = [2.7 +/- 0.7(stat) +/- 0.6(syst)]%. Comparisons are made with
results obtained at root s = 1800 GeV and with theoretical expectations.