Clarissa is generally regarded by critics to be among the masterpieces of eighteenth-century European literature. Influential critic Harold Bloom cites it as one of his favorite novels that he "tend[s] to re-read every year or so." The novel was well-received as it was being released. However, many readers pressured Richardson for a happy ending with a wedding between Clarissa and Lovelace. At the novel's end, many readers were upset, and some individuals even wrote alternative endings for the story with a happier conclusion. Some of the most well-known ones included happier alternative endings written by two sisters, Lady Bradshaigh and Lady Echlin. Richardson felt the story's morals and messages of the story failed to reach his audience properly. As such, in later editions of the novel, he attempted to make Clarissa's character appear purer while also Lovelace's character became more sinister in hopes of making his audience better understand his intentions in writing the novel.
The pioneering American nurse Clara Barton's full name was Clarissa Harlowe Barton, after the heroine of Richardson's novel.