An Imperative Duty is a short realist novel by William Dean Howells published in 1891.

The novel explores the idea of "passing" through the racially mixed character of Rhoda Aldgate, a young woman whose aunt informs her that she is one-sixteenth African American.

The book is about Rhoda Aldgate, a young woman who discovers she is one-sixteenth African American, after living her whole life as a white person.

In the nineteenth century, Rhoda's mother would have been referred to as an "octoroon."

The book is about a "Tragic Mulatta" character, a stereotype used by 19th-century American authors to explore racial miscegenation.