Members of the millennial generation spent last week getting slapped around in a Time cover story labeling them "lazy, entitled narcissists," living off their parents and Instagramming their irony. But at Sunday's birthday show for WRFF-FM (104.5), millennials were out in force and showing plenty of energy.

Though headliners Phoenix, fronted by 37-year-old Thomas Mars, were too advanced in age to qualify (and WRFF's six years on-air made it far too young), most of the day-long festival's acts were squarely in the millennial demo. (Rumors that Dicky Barrett, the Mighty Mighty Bosstones' positively ancient 48-year-old singer, would be sidelined for hip-replacement surgery proved unfounded.) Paramore's Hayley Williams started gigging in her mid-teens, while Passion Pit's Michael Angelakos started recording songs as a one-man band at the age of 20.

To the charge of arrested development, Passion Pit could at best plead no contest. Angelakos' songs lean heavily on the sound of throwback synths - a guitar made a brief, inaudible appearance during "Where I Come From." Angelakos, 25, sings in a near-perpetual falsetto and is given to lyrics like, "We've all got problems and we've all got something to say."

Paramore, which like Passion Pit played its contribution to a Twilight soundtrack, took a more aggressive approach to sincerity. The 24-year-old Williams ran out in a ripped Siouxsie and the Banshees shirt and zombie eye makeup and spent much of the band's set pumping her fists and kicking her feet.

Occasionally, she lay flat on the stage and sang at the ceiling, as if kicked back on her childhood bed. Although Paramore's self-titled fourth album debuted at the top of the charts last month, the band played only its two singles and otherwise stuck to past hits, with Williams taking the stance of a grateful up-and-comer rather than an established star.

With temperatures dropping and the evening wearing long, the audience started to filter out during Phoenix's set. But there were plenty left to cheer a well-designed set incorporating most of the French sextet's new album, Bankrupt!, and its predecessor, Wolfgang Amadeus Phoenix. Some of the subtleties of the band's airy, multlilayered sound were lost in the night air, but between Mars' polite inducements and Thomas Hedlund's insistent drumming, there was plenty to keep the crowd on their feet, and off their smartphones.