The articles printed here aroused more interest than I expected; consequently there have been requests for reprints which it has been impossible to supply from the stock available.

The solution, as I now realize, would have been to republish them at the outset. I was reluctant to do this without changes embodying later experience. However, rewriting is seldom successful, and much can be lost by the exclusion of tentative theories that show how ideas were developed. the articles are therefore reprinted without alteration. It will be seen that two do not belong to the series that originally appeared in Human Relations; the first is reprinted because it throws light on the origins of my belief that this approach merited further trial, and the last because it summarizes conclusions that I would like to have taken further, and that others might like to develop. I have also a purely personal reason for wishing to acknowledge the collaboration with John Rickman and the inspiration which his generosity and enthusiasm always engendered.

I regret not having discussed sovereignty and power. in small groups like those used here, power and sovereignty do not develop to maturity. the mature form is extrinsic and impinges on the group only in the form of invasion by . . .