A mental health worker in India who deals constantly with the stigma of mental illness in his own country was surprised to learn that this stigma exists in the United States. I wondered about the source of his surprise. Are we viewed as too educated, too enlightened, too wise to be guilty of intolerance? Gerhard Falk's latest book, Stigma: How We Treat Outsiders, suggests that anyone is a potential member of at least one stigmatized group and that most likely all of us, even the educated and enlightened, are capable of treating others differently because of our perception of them as "outsiders."

During his long career as an educator and author, Falk, a sociology professor at the State University of New York at Buffalo, has addressed specific types of stigma in various scholarly works, more than 50 in number. However, in this, his 12th book, he describes and discusses 13 different types of stigma, devoting a chapter to a description of the evolution and history of each type as well as research and statistics exploring the social consequences of that stigma.

Dr. Falk divides the 13 stigmas into two categories. Persons who are excluded because of a condition that they did not choose or over which they have little control may suffer from "existential stigma." Such conditions include mental illness, sexual identity, obesity, mental retardation, aging, marital status, and race (particularly for Native Americans). The second category, "achieved stigma," includes persons who have somehow contributed to their inclusion in a stigmatized group. Here Falk describes stigma associated with achievement, immigration, homelessness, prostitution, addiction (including alcoholism), and criminal conviction. Many of us fall into at least one of these categories and, with the inclusion of "resentment against achievement," no one seems to be exempt from membership of some stigmatized group.

Although such a vast array of "out-groups" suggests that Falk has covered them all, instead one begins to consider the insidious nature of stigma, and it seems that one stigma might lead to a spinoff stigma such that an insider group falls victim to its own judgment. For example, Falk describes how the stigma of obesity has created a multimillion dollar industry that often motivates unwarranted dieting by the "in-group"—those who are not obese. What he doesn't explore is the resultant out-group of persons who suffer from eating disorders that are perhaps in part a consequence of membership of an in-group that judged the obese.

The opening chapter reminds us of our long and shameful history of judging, condemning, and eradicating members of stigmatized groups. It also reminds us of the insights of Emile Durkheim, a "founding father of sociology," and thus helps us to understand why, despite education and enlightenment, we persist in our predilection toward identifying out-groups. Durkheim explained that, quite simply, out-groups create a sense of unity—and community—for the in-group. With a new sense of threat upon us, and an escalated and urgent need for unity and community, let us become students of stigma and not victims of our own in-group judgments.

Dr. Goldstein is associate professor of psychology at Samford University in Birmingham, Alabama.