The concept of accident-proneness is by no means a new one; but the term has passed into popular use, and although the colloquial usage of the term is frequently incorrect, yet the idea that some people are more liable to sustain accidents than their more fortunate fellows is now widely accepted. Of late years psychologists have made it their business to inquire into the nature of this susceptibility to accidents, and have found that whilst mankind in general is characterized by this proneness, there are individual differences in the degree to which it is possessed. In any sufficiently large observational group it is usually found that most of the accidents are sustained by a minority of the members of that group, and it is obviously of importance to discover what are the personal qualities or lack of abilities which make this minority specially accident-prone.