The CP-violating parameter sin 2B is directly measured using 110
pb-1 of data accumulated with the CDF detector at the Fermilab p anti-p
Tevatron collider operating at s**(1/2) = 1.8 TeV. The signal consists of 395
+/- 31 B0(d)/B-bar0_d --> J/psi K_S events. Three tagging methods are used to
identify the type of B mesons at production (B0(d) or B-bar0_d). From the CP
asymmetry, sin 2B is measured to be 0.79+0.41_-0.44, consistent with Standard
Model predictions. Sin 2B is in the interval 0