We report on preliminary measurements of time-dependent CP asymmetries in neutral B decays to CP eigenstates with transition amplitudes that are dominated by penguin-type loops. The results are obtained from a data sample of up to 227 million Upsilon(4S)->BB-bar decays collected with the BABAR detector at the PEP-II asymmetric-energy B-meson Factory at SLAC. The amplitudes of the effective mixing-induced CP asymmetries, sin(2beta)_eff, are derived from decay-time distributions of events in which one neutral B meson is fully reconstructed in a final state without charm and the other B meson is determined to be either a B0 or B0-bar from its decay products.