  A sample of 400 $B^0_d/\bar{B}{^0_d} \to J/\psi K^0_s$ decays collected in
$\bar{p}p$ collisions by the CDF detector is used to directly measure the
CP-violation parameter $\sin(2\beta)$. We find $\sin(2\beta) = 0.79
^{+0.41}_{-0.44}$,favoring the standard model expectation of a large $CP$
violation in this $B^0$ decay mode.
