After his auspicious debut, “Illmatic,” critics and fans heralded Nas as a hip-hop Wunderkind who could fuse the rhythmic poetry of Rakim with the social awareness of KRS-1 and Public Enemy.

But his sophomore album, “It Was Written,” failed to fulfill Nas’s early promise. Sure, it featured “If I Ruled the World,” his brilliantly crafted vision of a b-boy utopia featuring backing vocals by Lauryn Hill. But on other tracks, Nas succumbed to hip-hop’s romanticization of the drug trade by transforming himself into a cartoonish “gangsta” named Nas Escobar, after the late Colombian drug lord Pablo Escobar. While “It Was Written” sold more than 2 million copies, it left many fans wondering what had happened to their beloved street poet.

At its most thoughtful, Nas’s new “I Am” (Sony) marks a triumphant return of the rapper’s social consciousness. In one of the album’s most interesting songs, “I Want to Talk to You,” Nas demands “I want to talk to the mayor/to the governor/to the [expletive] president” to ask such questions as why “taxpayers pay for more jails for black and Latin faces” and why brothers “play with Playstations” while “they’re buildin’ space stations.”

Nas addresses problems within the hip-hop community in “We Will Survive,” in which he eulogizes slain rappers Tupac Shakur and the Notorious B.I.G. The song, a poignant addition to the sub-genre of hip-hop elegies, also links the trials of hip-hop artists to those of older black musicians, asking “What has Al Green seen to make him turn religious?” and “Did Smokey Robinson have to shoot his way out of war?”

As in the best hip-hop releases, lyrics are only part of the album’s allure. There’s also the arid grace of Nas’s voice and the often arresting musical tracks that exemplify various hip-hop aesthetics. Nas employs techno-funk producer Timbaland and his muse Aaliyah on “You Won’t See Me Tonight.” On “Nas Is Like,” producer DJ Premier represents the New York underground with a looping, broken-carousel sound that starts as an irritant and subtly becomes hypnotic. And “Hate Me Now,” Nas’s rousing radio-ready duet with Puff Daddy, bests Puffy’s own “Victory” and “Come With Me” for gothic hip-hop thrills with its soaring operatic backing vocals and slashing synthesized strings.

These songs showcase Nas at his best. But on too many other tracks, Nas once again gets caught up in the trappings of so much contemporary hip-hop. “Favor for a Favor” is a rote rap revenge scenario that wastes the considerable storytelling talents of Nas’s duet partner Scarface. And “Undying Love,” a rather horrific account of a man who kills his cheating lover, is a tale that is numbingly common in hip-hop. You’d think that most rappers find female autonomy as threatening as street thugs and racist cops.

Thematically, these bloody fantasies don’t sit well with the album’s realist concept and title. Perhaps one explanation for this is that Nas removed several tracks from the album as it was originally conceived after the tracks were bootlegged and made available over the Internet. Absent tracks such as “Project Windows,” about the Queensbridge projects where Nas grew up, “Belly Button Window,” in which Nas imagines life from the womb, and “Poppa Was a Playa,” in which Nas discusses his complicated relationship with his jazzman father, fit the album’s concept far better than their replacement tracks. Anyone with a good Web connection might wonder what a profound personal opus “I Am” could have been.