MANY PEOPLE think of narcissism as a poor personality trait and narcissists as people we should try to avoid. Sure, there's some truth to this, but moderate doses of narcissism are not only good, but also necessary, for our self-esteem, relationships and health, said clinical psychologist Craig Malkin, author of the new book Rethinking Narcissism: The Bad - and Surprising Good - About Feeling Special (Harper Wave).

Malkin, an instructor at Harvard Medical School, explains how narcissism, the drive to feel special, falls on a spectrum - and having either too little or too much of it can be unhealthy.

"You can think of narcissism kind of like a drug," Malkin said. "When people become addicted to it, that's when they venture into becoming narcissists or extreme narcissists."

The book includes a 30-question survey that allows readers to measure where they fall on the Narcissism Spectrum Scale, an assessment tool developed by Malkin and his colleagues. (Take a shorter version of this survey at drcraigmalkin.com/the-narcissism-test.)

Malkin explained that a moderate dose of narcissism is healthy. "If you feel a little special, it helps you see the world through rose-colored glasses. It helps you feel more optimistic and persistent in the face of failure. People who are high in healthy narcissism aren't especially modest, but they don't brag and they wouldn't hurt people in order to stand out."

Extreme narcissists, however, can be "argumentative, combative, hurtful and extremely entitled."