'We had a learning curve that worked out all right," says Josiah Johnson of the Head and the Heart.

The six-piece band has toured nearly constantly since it self-released its first album in June 2010 (the venerable Sub Pop Records rereleased it early the next year). They rose quickly from playing coffeehouses in their native Seattle to opening slots for bands such as Dr. Dog, My Morning Jacket, and the Dave Matthews Band. They headline the Tower Theater Friday night.

Johnson is one of the Head and the Heart's three vocalists and songwriters. He started the band with fellow guitarist and singer Jonathan Russell, and they recruited Charity Rose Thielen (violin, vocals), Kenny Hensley (keyboards), Tyler Williams (drums), and Chris Zasche (bass). Their nuanced folk-rock songs balance earnest introspection with communal enthusiasm, not unlike Fleet Foxes, the Avett Brothers, or the Civil Wars. Their second album, last year's Let's Be Still, broadens their palette with more buoyant vocal harmonies and subtle instrumental textures.

The band built its reputation on its live performances, and early on, it took every opportunity offered to be on the road.

"We just kind of said, 'Yes, yes, yes,' and before you know it, a couple years had gone by," Johnson says. "It's one of those things that I am glad we did it the way we did because it helped us grow. But it's nice now and more livable now to take the best things and be able to turn things down and keep things a little more sane and keep your head together."

But with its success, the band has had to find ways to translate its subtleties to ever-growing stages, especially as a headlining act expected to command a large venue such as the Tower.

"Fortunately, our transition into those large places has occurred fairly naturally," Johnson says. "Things started happening rapidly, but we stepped up gradually. We didn't go from playing to 500 people to playing to 5,000 people. Over the course of five years, we played to 500, 800, 1100, 1700. Every time you make a jump from one to the next, it takes some getting used to, but it's not such a crazy leap that you feel like you've lost the room."

Johnson credits Philly's Dr. Dog with helping provide a road map to that balance of careful song craft and energetic performance, of introversion and extroversion, of, well, the head and the heart.

"That was our first big tour. We're all huge fans of those guys," Johnson says. "I'd already seen them three or four times. But I started to get the sense that was a little bit of our identity, too. In my mind, they put out these great albums that are pop albums, but their live show takes the energy up, like, five notches. That's something that we've tried to do."