  We present a preliminary measurement of CP-violating parameters S and C from
fits of the time-dependence of B0 meson decays to eta' K0. The data were
recorded with the BaBar detector at PEP-II and correspond to 227 * 10^6 B-Bbar
pairs produced in e+e- annihilation through the Upsilon(4S) resonance. From a
maximum likelihood fit we measure the CP-violation parameters S = 0.27 +/- 0.14
(stat) +/- 0.03 (syst) and C = -0.21 +/- 0.10 (stat) +/- 0.03 (syst).
