We derive electric fields for the purpose of controlling molecular processes taking the instantaneous dynamics of the molecule into consideration. In this way, it is not only possible to achieve a highly efficient control but, more importantly, to give the derived fields a clear physical interpretation. The scheme is illustrated for the cases of excited state IR dissociation of NaI and for a protontransfer process, treated within a simplified model. (C) 2004 Elsevier B.V. All rights reserved.