Songfacts®:

• This is the first single by Rock band Panic At The Disco's third album, Vices & Virtues. The song was released on February 1, 2011 and marked the debut of Panic's new two-man lineup after the exit of Ryan Ross and Jon Walker, leaving as the remaining duo singer/multi-instrumentalist Brendon Urie and drummer Spencer Smith.
• Urie explained to MTV News that the single and the album are intrinsically linked. "Basically, all of the songs, including 'Mona Lisa,' kind of touch on what the album is called. It's called Vices & Virtues, and in one way or the other, at least one to 10 virtues or vices are represented in every song," said the singer. "[It's] little minor things I didn't know were vices or virtues, until we looked them up. I was like, 'I don't know what altruism means, so I'll look that up.' Things like logic, pride, vanity — it can go either way. So it was kind of interesting to read about that. And it just made sense, because all the songs [on the album] are so all over the place," he continued. "They don't sound anything like each other, and it's like, 'How does this all tie together?' and then it kind of made sense. It was kind of lucky."
• The music video was shot in Los Angeles with director Shane Drake, who previously directed the group's clips for "Nine in the Afternoon" and "I Write Sins Not Tragedies." The clip runs through traditions of mourning and stages a funeral in an alternative universe. The video's concept is partly about saying goodbye to the band's past and bears many similarities to the "I Write Sins Not Tragedies" promo, from the church setting to various camera shots (the dusty top hat resting on a church pew is the same one for "Sins"). "When we were talking about the concept, somebody had the idea to kind of tie in to the beginning of the 'Sins' video, and we realized it would work with it," Spencer Smith told MTV News. Another nod to the band's past is that the clocks on the wall are all set to nine o'clock, in honor of their "Nine In The Afternoon" video.
• Urie explained the meaning of this anthemic power-rock ballad to Spin magazine: "On the surface it can seem like just the story of drama between a guy and a girl. But it's really about what I've been going through, an inner-struggle within myself, and fighting the dualities of my personality - the side that f--ks everything up and destroys everything and the other side that tries to pick up the slack."
• Urie came up with the original idea for this song before the band had even started touring on their 2008 album Pretty. Odd. He told MTV News: "It was just sitting in my laptop collecting figurative dust on my hard drive, not really doing much."