Long Island rockers Taking Back Sunday have reason to celebrate.

Fifteen years into their career, the group is still muscling their way onto the Billboard charts, this time with the release of their sixth studio outing "Happiness Is." And while the alt-rockers continue to represent the Tri-State area proudly, their path to stardom was built on numerous line-up changes that could have easily torn them apart.

Back in 1999, founder Eddie Reyes brought together a mish-mash of alternative musicians from the Long Island rock scene to form the initial lineup. But after tinkering with several vocalists, Reyes decided bassist Adam Lazzara should front the group instead of original singer Antonio Longo. Thus began the musical chairs that would define the next decade.

After touring extensively and releasing the debut EP "Tell Your Friends" in 2002, the group was off and running. But in 2003, their lineup once again changed when guitarist John Nolan and bassist Shaun Cooper decided to leave the group in favor of another band. Taking Back Sunday persevered however, and the group managed to score a major record deal with Warner Bros. in 2005.

This led to the 2006 release of "Louder Now," the record that truly catapulted the band into the mainstream. Once again, however, turmoil within the group forced the departure of guitarist Fred Mascherino. And despite the successful release of 2008's "New Again," Taking Back Sunday suffered even more turnover in 2010 when Matt Rubano and Matthew Fazzi announced that they were no longer part of the group due to conflicts over the writing process.

What could have served as the final note for Taking Back Sunday actually paved the way for a reunion instead. In 2010, guitarist John Nolan and bassist Shaun Cooper returned to Taking Back Sunday and together the group released a new self-titled album in 2011.

Which brings us to the here and now. Free from any further lineup changes, Taking Back Sunday released "Happiness Is" this past month, which debuted at No. 10 on the Billboard charts. In a way, the album title should have been called "Happiness Is...Staying Together."