Susan Elizabeth Phillips was born on December 11 in Cincinnati, Ohio (U.S.A.) to John Aller Titus and Louesa Coate Titus. After receiving a B.F.A. in theater arts from Ohio University, Phillips taught drama, speech, and English at a local high school until her first child was born, then became a stay-at-home mother. In 1976, the family moved from Ohio to New Jersey, where Phillips became best friends with her neighbor Claire Lefkowitz. Phillips and Claire often discussed the books they liked to read, and one day decided to write a book together. After several months, they came up with a system for collaborating on a historical romance. Their book, The Copeland Bride, was purchased by the first editor to read it, and was published in 1983 under the pen name Justine Cole.
Phillips found that she really enjoyed writing. Claire and her family moved shortly thereafter, and Phillips had to learn to write a story by herself. She was successful, and her subsequent novels, published under her own name, have reached the USA Today and New York Times bestseller lists. She is the only five-time winner of the Romance Writers of America Favorite Book of the Year Award. In 2001, Phillips was inducted into the Romance Writers Hall of Fame and in 2006 was a recipient of the Romance Writers of America's Lifetime Achievement Award.
Phillips and her husband, Bill, met on a blind date while in college. They have two grown sons, and currently live in Chicago, Illinois.