Essays in Biography is a play on words conveying Carl Rollyson's attempt to explore the nature of biography in pieces about the history of the genre and in portrayals of biographers (Plutarch, Leon Edel, and W. A. Swanberg), literary figures (Lillian Hellman, Jack London), philosophers and critics (Leo Strauss and Hippolyte Taine), political figures (Winston Churchill and Napoleon), and artists (Rembrandt and Rubens).

An essay in biography, Rollyson argues, is an effort to comprehend a life that is inherently incomplete and subject to revision. Many of the facts about a biographical subject's life that are blandly presented in reference books have been discovered by biographers at great cost to their reputations. With the history of biography as a censored genre in mind, he encourages consumers of biography to be critical of the biographies they come across - no matter whether those biographies are book-length narratives or short encyclopedia entries.

Many of the pairings in Essays in Biography are meant to evoke Plutarch's presentation of "parallel lives". The biographical essay, Rollyson concludes, is a unique form of knowledge, one that modern critics have devalued by trying to separate the creator from his creation.