Joey Bada$$ burst onto the hip-hop scene last year with his 1999 mixtape, a dedication to early-1990s boom-bap rap, and a whole crew behind him proudly touting their Pro Era credentials. In the intervening year, the P.E. Conglomerate has released a collaborative mixtape, PEEP: The aPROcalypse, and supported Joey as he released his Summer Knights tape this July and went on a whirlwind tour earlier this year alongside Flatbush Zombies and The Underachievers. Yet despite Joey's insistence on bringing his crew along with him—he'll rarely do interviews without at least one other Pro Era member by his side, and often insists on keeping production and features on his releases in-house—many of Pro Era's myriad MCs and producers have skated by under the radar, quietly putting out singles and contributing verses to posse cuts without raising much noise in the mainstream scene. Now, after the release of Summer Knights and with a slew of Pro Era projects slated to come out later this year, XXL has dug deep into the crew's back catalog to give you the rundown on some of the major players—both rappers and producers, artists and hype men, third eye aficionados and hook specialists—that together help to make up Pro Era.—Dan Rys (@danrys)