Maybe you lack the instinct for self-promotion. Maybe you can't muster your employer's rah-rah-rah-sis-boom-bah attitude. Maybe you'd rather stay home and read a novel instead of going out to the party of the year. So? Something's the matter with you, and you should feel ashamed, right?

Wrong, says Susan Cain, author of Quiet, a vigorous, brainy and highly engaging defense of introversion. A self-proclaimed introvert herself, Cain examines in the first part of her book how our one-time "Culture of Character," which gave roughly balanced respect to the positive characteristics of both introverts and extroverts, shifted to our contemporary "Culture of Personality," a culture of marketing and self-marketing that almost exclusively (and to our peril) favors the risk-takers, the quick-decision-makers: in short, the extroverts.

Drawing on cultural histories and fascinating recent research in psychology and brain-function science, Cain challenges such misconceptions as "the myth of charismatic leadership," the utility of group brainstorming and the idea that introversion is the result of bad parenting instead of an innate personality characteristic. "Probably the most common—and damaging— misunderstanding about personality types is that introverts are antisocial and extroverts are pro-social," she writes. "But as we've seen, neither formulation is correct; introverts and extroverts are differently social." In the final section of her book, she offers sensible advice on strategies that introverts can use to succeed in a society that operates within a value system she calls the "Extrovert Ideal"—without betraying their essential selves.

Cain enlivens her discussion with road trips and case studies. She skeptically enrolls in a seminar given by Tony Robbins, who is probably the extrovert ideal incarnate. She visits students and professors at Harvard Business School and Asian-American students in Silicon Valley. She cites the experiences of Rosa Parks and Mohandas Gandhi. She interviews husbands and wives, parents and children.

Cain says her "primary concern is the age-old dichotomy between the ‘man of action' and the ‘man of contemplation,' and how we could improve the world if only there was a greater balance of power between the two types." Hers is surely an argument worth talking about.

The introvert/extrovert dichotomy is easily stereotyped in psychological literature: extroverts are buoyant and loud, introverts are shy and nerdy. Here, former corporate lawyer and negotiations consultant Cain gives a more nuanced portrait of introversion. Introverts are by nature more pensive, quiet, and solitary, but they can also act extroverted for the pursuit of their passions. Cain describes and explicates the introvert personality by citing much research (at times so much that readers may be confused about what she is explaining) and going undercover, at one point immersing herself at a Harvard Business School student center and, in a very amusing chapter, at a Tony Robbins seminar, among other case studies. Cain's conclusion is that the introversion or extroversion personality trait is not as simple as an on/off switch but a much more complex expression of a personality. VERDICT This book is a pleasure to read and will make introverts and extroverts alike think twice about the best ways to be themselves and interact with differing personality types. Recommended to all readers.—Maryse Breton, Bibliothèque et Archives nationales du Québec, Montreal

While American culture and business tend to be dominated by extroverts, business consultant Cain explores and champions the one-third to one-half of the population who are introverts. She defines the term broadly, including "solitude-seeking" and "contemplative," but also "sensitive," "humble," and "risk-averse." Such individuals, she claims (though with insufficient evidence), are "disproportionately represented among the ranks of the spectacularly creative." Yet the American school and workplace make it difficult for those who draw strength from solitary musing by over-emphasizing teamwork and what she calls "the new Groupthink." Cain gives excellent portraits of a number of introverts and shatters misconceptions. For example, she notes, introverts can negotiate as well as, or better than, alpha males and females because they can take a firm stand "without inflaming counterpart's ego." Cain provides tips to parents and teachers of children who are introverted or seem socially awkward and isolated. She suggests, for instance, exposing them gradually to new experiences that are otherwise overstimulating. Cain consistently holds the reader's interest by presenting individual profiles, looking at places dominated by extroverts (Harvard Business School) and introverts (a West Coast retreat center), and reporting on the latest studies. Her diligence, research, and passion for this important topic has richly paid off. (Jan.)