We present a measurement of CP-violation parameters in the b→sq̄q penguin transitions (q = s,u,d) based on a 78 fb-1 data sample collected at the Y(4S) resonance with the Belle detector at the KEKB energyasymmetric e+e- collider. One neutral B meson is reconstructed in the φKS 0, K+K -KS 0, or η′ KS 0 decay channel, and the flavor of the accompanying B meson is identified from its decay products. CP violation parameters for each of the three modes are obtained from the asymmetries in the distributions of the proper-time intervals between the two B decays. © 2003 The American Physical Society.