If there were a time for its comeback, though, it would be now, in the face of occupations, of continued recession, of deflated idealism. And yet current economic realities have made almost no mark on hip-hop this year. Preaching, which would have been a perfectly acceptable mode in the 1990s, would likely be all but ignored in today’s hip-hop.

Instead the battle lines have been redrawn in novel ways, and message-driven hip-hop has begun to find a home again, not just on the fringes, but near the center of the genre. Nowhere is that clearer than in the success of Kendrick Lamar, a young rapper from Compton, Calif., and a vivid stylist who’s succeeding possibly in spite of his thoughtfulness. Last summer, he released “Section.80” (Top Dawg), a startlingly beautiful album that recalls the early- to mid-’90s semiactivist jazz-influenced hip-hop of Digable Planets and, crucially, the Los Angeles underground heroes Freestyle Fellowship, who took their social concerns and created new ways of rapping to reflect them.

In a coincidence of scheduling on Monday night, Common performed at the Highline Ballroom and Mr. Lamar at S.O.B.’s, showing the contrast between being socially minded then and now. There’s an ease to Common’s presence that’s inclusionary; his vision is earnest and open. “I’m to hip-hop what Obama is to politics,” Common raps on his new album — groan. Righteousness is not its own aesthetic reward.

There was something wily about Mr. Lamar during his performance, though. He’s an enlightened thinker, but hardly a preacher. Nor is he flamboyant in his beliefs. What he is is committed and savvy, an artist putting his ample charisma in the service of greater ideas. Sometimes he’s straightforward — his song “No Make-Up (Her Vice)” is the sort of empowerment anthem that will be familiar to any longtime fan of Common’s romantic side. But the songs that received the most enthusiastic response during this show were the difficult ones, like “A.D.H.D.”

Mr. Lamar evidently enjoys the challenge of bridging worlds. His highest-profile moment this year was probably his arresting guest verse on Drake’s “Take Care,” on which he talks about the seductions of fame, about needing a strong backbone to hold onto one’s principles, and about ultimately giving in. He’s a pragmatist and an agitator all in one. He accepts the system as it is, and tries to use it to his advantage. That doesn’t necessarily mean that social conscience and financial success are more reconcilable now than they have been in the past, but rather that the ways that they intersect have become trickier and more subtle.