We present a measurement of the hadronic invariant mass squared (MX2) spectrum in charmed semileptonic B meson decays B→Xc ν based on 140fb-1 of Belle data collected near the Υ(4S) resonance. We determine the first, the second central, and the second noncentral moments of this spectrum for lepton energy thresholds ranging between 0.7 and 1.9 GeV. Full correlations between these measurements are evaluated. © 2007 The American Physical Society.