A novel characterization of bumpless transfer among alternative controllers, both in continuous and discrete time, is introduced. The bumpless transfer problem is to design a compensation scheme guaranteeing an L-2 (respectively, l(2)) bound on the mismatch, after the switching time between the actual plant output and a particular target, ideal response. Minimization of the gain from initial plant state mismatch to L-2 (respectively, l(2)) plant output mismatch provides improved transients. A solution to the bumpless transfer problem is given, both for plants without input saturation and for plants with input saturation. The solution guarantees anti-windup features in the latter case. (c) 2005 Elsevier Ltd. All rights reserved.