When Long Island, N.Y., emo band Taking Back Sunday released its debut album, “Tell All Your Friends,” in 2002, bassist Shaun Cooper says he didn’t expect the success it received.

“I thought we got lucky enough to sign a record deal,” Cooper says. “That record came out in March. I thought we would tour the summer, and then I would go back to college and figure out what I was going to do with my life.”

“Tell All Your Friends” not only hit platinum, but paved the way for Taking Back Sunday to be signed to Warner Records for its third album, 2006’s “Louder Now,” which reached No. 2 on Billboard’s Albums chart and produced three charting hits: “MakeDamnSure,” a Top 10 on the Alternative charts, “Twenty-Twenty Surgery” and “Liar (It Takes One to Know One”).

This year marks the 20th anniversary of the release of “Louder Now,” and Taking Back Sunday is on tour to celebrate that benchmark.

The group headlined the Wind Creek Steel Stage at PNC Plaza, Musikfest, Bethlehem, at 6 p.m. Aug. 8, with platinum-selling pop-punk bands Yellowcard and The Click Five.

It was the first time in more than a dozen years that Taking Back Sunday played in the Lehigh Valley.

“So I’m still waiting for the other shoe to drop - when I have to go back to school and figure stuff out,” Cooper says in a phone interview from his home on Long Island.

“But living the dream. It’s really incredible the band has had this longevity. [“Louder Now”] was a huge record for our band. And I just can’t believe that we’re here and people are still responding to the songs.

“Every day feels like borrowed time, so I don’t want to take anything for granted.”

A break

Cooper said that unexpected success caused him and guitarist John Nolan to leave Taking Back Sunday in 2003.

“When Taking Back Sunday charted, it was so wild to be thrust from my bedroom in my parents’ house to be on tour all of the time,” Cooper said.

“It turned my world upside down. Really, I was living at home with my parents, I was in my early 20s. It was really great just to be on the road all the time ... to tour in a tour bus, having people set up your gear. And then not only is it all happening, it’s happening so fast.

“I was not prepared for that kind of success, so I was not equipped or motivated to put in the time and effort that the band needed to be successful and to sustain the success all this time later. So I needed to step back. I needed to take my time.”

He said Taking Back Sunday guitarist John Nolan “had said the same thing to me, we had talked: ‘We can’t do this like this. We need more time; we need more space. Things are moving at kind of way-too-rapid pace and I don’t know what’s going to happen, personally.’ So I need to pull back.”

Cooper and Nolan started the band Straylight Run, whose self-titled debut album hit Billboard’s Top 100.

Taking Back Sunday “wanted to keep moving on,” so Cooper said he told Nolan, “ ‘OK, let’s just hang out.’ We were hanging out all the time, so we were going to bars every night at home, not thinking about being in Taking Back Sunday anymore.

“So John was, like, ‘Why don’t we just start working on some songs? Just us.’ I said, ‘OK, cool. You got some cool ideas, I got some cool ideas. Maybe there’s something there.

“So it kinda started like that. It wasn’t like this massive plan, ‘We’re gonna form another band.’ It was just out of fun. And there was a huge bit of naivety. I was happy to not be successful. I was happy to go back to my parents’ bedroom and not be successful at all.

“So we did it at a much slower pace. We did not have near the success that Taking Back Sunday had, but we were very content with what we had. … So I said, ‘That was a good run. I created two bands, I met my wife.’”

A reunion

After “Louder Now,” Taking Back Sunday released the 2009 album “New Again,” which hit the Top 10, but did not achieve the commercial success of those earlier albums.

Cooper said he was about to reach out to his uncle, who worked for Amtrak, to look for a job outside music when, about one month later, Taking Back Sunday called and asked, ‘Would you and John want to come back into the band?’

“And I said, ‘Man, maybe the time is right this time.’ And we hit it off again; we connected in a way that we hadn’t previously. So those seven years were so beneficial for me and exactly what I needed at that time.

“And it was better than I ever imagined, and I’m still here and having a blast.”

The next album, 2011’s “Taking Back Sunday,” reached No. 4 on the Rock chart, as did 2014’s “Happiness Is.” In 2016, “Tidal Wave” reached No. 6. The band’s most recent disc was “152” in 2023.

The new tour pairs Cooper with Fred Mascherino, the guitarist who took over for Nolan when he and Cooper left Taking Back Sunday.

Nolan recently took time off to have neck surgery, “which is really concerning,” Cooper said. “And we weren’t sure what we were going to do.

“And we had reconnected with Fred, and when John decided to take time off, [lead singer] Adam [Lazzara] and I we said, ‘Well, the only way it can kind of work is if we can get Fred involved, and let’s see.’

“We asked Fred and he was down, and we did a rehearsal and it worked really well. And he’s just such an outstanding musician and a great guy to be around and he works so hard. So I’m really enjoying the show.”

‘Wonderful thing’

Cooper said that, 20 years later, the songs from “Louder Now” connect, “I think, now more than ever.

“All the trials and tribulations the band has been through, I can remember when those songs were written,” he said. “I remember being in the practice room when, maybe, Adam came up with that vocal melody, or John came up with that guitar part.

“It’s so fun to connect with that and to see people this many years on still responding to those songs, because I have the bands that did that for me ... the bands that inspired me coming up.

“And we’re still able to do this at such a great level, and still have such a passion for it, such an appreciation for it. I just appreciate the guys in my band, and I’m in awe of all their talent. Everyone up on that stage is working so hard and I think we all kind of feel that.

“And then to hear the crowds cheer ... It seems to be getting bigger and bigger, and there’s such a good sense of community. The husbands and wives have met at our shows, and now they bring their kids. It’s really surreal to me to see that is happening. That’s a thing that I’m part of, and I’m so grateful for it.”

Asked what it means to play songs such as “MakeDamnSure” or “Liar” after these years, he says, “I think it’s one of those things . Every time people are responding to our songs, especially the older ones, you remember the humble beginnings of the band, and then just see where you are now.

“And so every night just kind of takes on a life of its own. You see people responding during a solo, and it’s, like, ‘Oh my God, I can’t believe this.’ Fred, our guitarist, playing a guitar solo and then Nathan, who also plays guitar, plays a harmony over it, and it’s one of the coolest moments in the show to me.

“So it’s kind of new, to me, playing that song. So you remember the humble beginnings of the band. You see the people responding to those words and singing along, and then you have cool moments like that happening.

“And every night is so moving and it feels new every night ... because it is. There’s different energy depending on the crowd, there’s different energy.

“Like, in Bethlehem, we’re playing with Yellowcard, I think there’s going to be a massive crowd there, and that’s going to be a little different from when we play our own shows, where it’s just us headlining. So you get something new out of it every night.

“The thing is, we created these songs with our friends and we still get to do it. And that’s a wonderful thing.”

Yellowcard, Taking Back Sunday, The Click Five, 7 p.m. Aug. 8, Wind Creek Steel Stage at PNC Plaza, Musikfest, Bethlehem.