I wish to make it clear to any would-be reader of this volume that it is a sequel to my _Introduction to Social Psychology_, that it builds upon that book and assumes that the reader is acquainted with it. That former volume has been criticised as an attempted outline of _Social Psychology_. One critic remarks that it may be good psychology, but it is very little social; another wittily says “Mr McDougall, while giving a full account of the genesis of instincts that act in society, hardly shows how they issue into society. He seems to do a great deal of packing in preparation for a journey on which he never starts.” The last sentence exactly describes the book. I found myself, like so many of my predecessors and contemporaries, about to start on a voyage of exploration of societies with an empty trunk, or at least with one very inadequately supplied with the things essential for successful travelling. I decided to avoid the usual practice of starting without impedimenta and of picking up or inventing bits of make-shift equipment as each emergency arose; I would pack my trunk carefully before starting. And now although my fellow travellers have not entirely approved my outfit, I have launched out to put it to the test; and I cannot hope that my readers will follow me if they have not at their command a similar outfit—namely, a similar view of the constitution of human nature. I would gratefully confess that the resolve to go forward without a further long period of preparation has been made possible for me largely by the encouragement I have had from the recently published work of Dr James Drever, _Instinct in Man_. For the author of that work has carefully studied the most fundamental part of my _Social Psychology_, in the light of his wide knowledge of the cognate literature, and has found it to be in the main acceptable.