A fully-relativistic restricted active space (RAS) configuration interaction (0) approach is employed to compute the P,T-odd interaction constant W-d of the ground ((2)Sigma) state of YbF. A series of increasingly sophisticated Cl space yields a best estimate of W-d = -1.088 X 10(25) Hz/e-cm. The Cl space that yields the best estimate of W-d is also used to compute other molecular properties, all of which are found to be in good agreement with experiment. (c) 2005 Elsevier B.V. All rights reserved.