In 2002, Sossamon starred in Miramax Films' romantic comedy 40 Days and 40 Nights, as Erica Sutton, the love interest of Josh Hartnett's character, Matt Sullivan. It received mixed reviews from critics, but was a major box office success, earning a worldwide total of US$95,146,283 on a production budget of US$17 million. Sossamon's part gained critical acclaim in general; About.com noted that she was "already making a name for herself as a romantic leading lady. With starring roles opposite two of Hollywood's hottest young actors (Hartnett and Heath Ledger) under her belt, Shannyn's star is rising fast. Her exotic looks separate her from the pack, and her performances have, thus far, been exceptional". Praising Sossamon and co-star Harnett, Elvis Mitchell wrote for The New York Times: "Mr. Hartnett matches up with Ms. Sossamon, and not only because their eyebrows signal that they are both Vulcans. She is a more direct performer; what she does is not acting – yet – but she can look as if she's listening. Her approach contrasts hilariously with his gentility". Afterwards, both actors received a Teen Choice Award nomination for "Choice Film Chemistry".
