Romantic suspense novels are often similar to mysteries, crime fiction and thrillers, and paranormal romances use elements popular in science fiction and fantasy novels.

1. Contemporary romance, which is set after World War II, is often what people mean when they refer to a romance novel. Contemporary romance novels—the largest sub-genre—are set in the time when they are written, and usually reflect the mores of that time. Heroines in contemporary romances prior to 1970 usually quit working when they marry or have children—while heroines after 1970 usually have, and keep, a career. As contemporary romance novels have grown to contain more complex plotting and more realistic characters, the line between this sub-genre and the genre of women's fiction has blurred.

2. Historical romance is set before World War II. This subgenre includes a wide variety of other subgenres, including Regency romance. Historical romance novels are rarely published in hardcover, with fewer than 15 receiving that status each year, less than one-fifth of the number of contemporary romance novels published in that format. Because historical romances are primarily published in mass-market format, their fortunes are tied to a certain extent to the mass-market trends. Booksellers and large merchandisers now sell fewer mass market paperbacks, preferring trade paperbacks or hardcovers, which prevents historical romances from being sold in some price clubs and other mass merchandise outlets.