In The Secret Life of Pronouns, social psychologist and language expert James W. Pennebaker uses his groundbreaking research in computational linguistics-in essence, counting the frequency of words we use-to show that our language carries secrets about our feelings, our self-concept, and our social intelligence. Our most forgettable words, such as pronouns and prepositions, can be the most revealing: their patterns are as distinctive as fingerprints.

Using innovative analytic techniques, Pennebaker X-rays everything from John McCain's tweets to the Federalist Papers. Who would...