A few years ago, at the end of a lecture on handedness, a neuropsychology graduate student asked, “Why should I care about handedness? Left-handedness is not a disease.” She had missed the main point of the lecture, namely that left-handedness is an exciting experiment of nature. In the left-hander we find the opportunity to study a healthy brain that is organized differently from other healthy brains. Here is a chance to study the effects of neural diversity without the vagaries of pathology. The study of handedness differences is not just about handedness.