An apparatus for adaptive sheet decurling in an electrophotographic printing machine. A plurality of sensors are provided to determine the basis weight of the copy sheet, the density of the image being transferred to the copy sheet and fused thereon, the relative humidity of the machine environment, the process speed of the print engine, and any other relevant parameters. Signals indicative of these parameters are generated and sent to the machine controller which processes these signals and predicts the degree and direction of curl expected in a sheet. Based on the degree of and direction of curl, a bidirectional variable penetration decurler is actuated to a setting which should provide the proper amount of mechanical decurling force.