"Now You Know" is the fourth season premiere episode of the American comedy-drama series, Desperate Housewives, and the 71st episode overall. The episode premiered on American Broadcasting Company (ABC) on September 30, 2007. It was written by series creator Marc Cherry and directed by Larry Shaw.

The fourth season of Desperate Housewives, an American television series created by Marc Cherry, premiered on September 30, 2007, on ABC. Filming for the series was interrupted by the 2007–2008 Writers Guild of America strike in November 2007, after production on the two-episode tornado storyline wrapped. The first part, "Something's Coming", aired on December 2, 2007. "Welcome to Kanagawa", the second part and the last episode filmed before the strike, was originally going to be aired after the strike's resolution, but aired on January 6, 2008. Seven additional episodes were produced for the fourth season after the strike, the first of which aired on April 13, 2008. The final two episodes served as a two-part finale and were aired consecutively on May 18, 2008. A total of 17 episodes aired as part of the season, with one recap special airing on September 23, 2007.