If you’re a fan of the play or movie Sound Of Music, you might’ve been one of the  18.6 million viewers who watched the live performance of Sound Of Music last week on  NBC. The show starred Carrie Underwood as Maria , and True Blood star Stephen Moyer as Captin Von Trapp.

With 18 months of planning Producers Neil Meron and Craig Zadan explained how NBC wanted to cast a well known name to play the role of Maria. Carrie Underwood, the American Idol winner, and country music star was not the first choice for the role. NBC was interested in casting Anne Hathaway as Maria, but Hathaway could not commit to rehearsals and the schedule for the broadcast. However, Carrie Underwood was a good choice “I’m not sure almost 20 million people would have come out for a lot of other names.” said Robert Greenblatt, chairman of NBC. “Social media played a pivotal role in the success of the show,” Mr. Zadan said, noting Twitter and Facebook traffic “that lasted the entire performance and beyond.”

NBC announced that they will put on another live broadcast of another Broadway play next year for the holidays. “Rights holders of musicals have said, ‘Please do one of our shows.’ We’re excited to try it again.” said Greenblatt.  The next live broadcast should not take as long as 18 months to prepare. “We worked on this one for at least 18 months,” he said. “Now that we have done it once, we don’t need 18 months again. We know a lot about how to do it.”