Jamie Sierota and Sydney Sierota of Echosmith perform at Jammin' Java in Vienna on Nov. 12. (Kyle Gustafson/For The Washington Post)

Echosmith is the indie-pop equivalent of the Partridge Family. The four-piece band, consisting of siblings Jamie, Noah, Sydney and Graham Sierota, was all smiles and sunny positivity on Wednesday night as the group brought its debut album, “Talking Dreams,” and hit single “Cool Kids” to Vienna’s ­Jammin Java. The venue, nestled in a suburban strip mall, was the perfect place for the show, allowing the band — the members range from 15 to 21 years old — to play to a crowd of their peers: teens (and possibly preteens) who took selfies without leaving the sight of watchful parents.

The male band members wore blazers and buttoned-up paisley shirts; Sydney opted for a floral print dress. Their brand of pop-rock was as gentle and pristine as their outfits, with hum-along harmonies, hummingbird chords and toe-tapping backbeats. They softened the edges of bands such as Metric, the Killers and (another group that kept it all in the family) Eisley, nodding to Afrobeat-obsessives Vampire Weekend, faux-folkers Mumford and Sons and country rebel Kacey Musgraves. ­Basically, fans of any guitar-based act from this millennium heard something familiar and could find something to like.

There was also a hint of new wave in the set, courtesy of the keyboard melodies in songs such as “Come Together” and faithful but personal covers of Talking Heads’ “This Must Be the Place” and Modern English’s “I Melt with You” — songs by bands that broke up before anyone in Echosmith (or most of the audience) was born.

Despite its youth, Echosmith has stage presence and performance down pat. Lead vocalist/frontwoman Sydney was all dramatic hair flips and hand gestures. She complemented her pleasant voice with a keyboard, a drum, and — at one point, inexplicably — a parasol. Lanky bassist Noah bounced across the stage with rock star facial expressions, while Jamie (the eldest Sierota) was mostly stoic behind his guitar.

They seemed pleasantly surprised by the sold-out crowd as they exuberantly chatted about being “super-stoked” and “literally” living their dreams. At several points, Sydney photographed and filmed the crowd with her smartphone; when she brought the crowd together for a photo, the prompt was to act like they were “excited about life.” The band even collected donations for a school in the Philippines.

Sydney Sierota of Echosmith performs at Jammin' Java in Vienna, VA. The band's hit song "Cool Kids" reached the #13 on the Billboard Hot 100 chart. (Kyle Gustafson/For The Washington Post)

Echosmith might be the most earnest act to ever play Jammin Java, which is saying something for a venue that hosts more than its share of acoustic troubadours. Even the most jaded cynic couldn’t blame the band for being so sincerely intense and intensely sincere — they’re still kids, after all. As Modern English sang all those years ago, “The future’s open wide.”

Kelly is a freelance writer.