Though it’s filled to the brim with self-deprecatory jibes about the inferiority of sequels, “22 Jump Street” is the rare follow-up that improves on its predecessor. The 2012 spoof of Johnny Depp’s eighties Fox series showed that Jonah Hill and Channing Tatum made a good comedic team, and for its first half it offered a solid blend of farce and action. But it deteriorated badly in the second hour, giving way to an excess of raunchiness and bombastic, poorly-choreographed set-pieces. “22 Jump Street,” by comparison, doesn’t eliminate the raunchiness completely, but reduces it substantially, and the action sequences are much wittier and well-shaped this time around. And since Hill and Tatum continue to play off so well against one another, the result is an enjoyable ride, from an initial slapstick chase scene down to a final-credits joke about future installments in the series that’s worth staying around for.

The plot is essentially what Chief Hardy (Nick Offerman) says it is in giving doofus officers Schmidt (Hill) and Jenko (Tatum) their new assignment (going undercover on a campus, though this time at the collegiate rather than the high school level): the same thing as before, though he adds that it’s always worse the second time around. Their first mission, involving lectures from an online university, brings them literally face-to-face with exotic animals being fenced by a crime lord called Ghost (Peter Stormare). It goes badly, ending up with the partners dangling from a speeding eighteen-wheeler.

The second, however, takes the duo back under the direction of volatile Captain Dickson (Ice Cube) of the reconstituted Jump Street unit (moved across the street from a shuttered Korean church to a closed-down Vietnamese one) and onto an actual campus, where they again enroll as pseudo-students Doug and Brad McQuaid to ferret out the dealer of a new drug called WyFy implicated in a coed’s death. (Jenko remarks in an awestruck tone that he’s the first in his family to pretend to go to college.) Needless to say, their bumbling investigation does not go particularly well, but their efforts to fit in bring about the real centerpiece of the script: the effect that college life has on their closer-than-close camaraderie. In effect the picture becomes a dippy send-up of Hollywood conventions, with their bromance threatened when Jenko falls in with the fraternity headed by Zook (Wyatt Russell), quarterback of the football team, who becomes his best buddy when Jenko proves to be not only a kindred wild spirit but the perfect receiver on the field.

In a reversal of the first movie, though, while Jenko fits in perfectly with the hard-drinking frat crowd, Schmidt is dismissed as a nerdy schlub and feels betrayed by his partner, especially since he suspects that Zook is the dealer they’re looking for. His loneliness isn’t even assuaged by a budding romance with pretty Maya (Amber Stevens), who just coincidentally proves to be…no, that would be spoiling things. Suffice it to say that after a campus chase in which Ghost and his henchmen use a Hummer to pursue our heroes, who are ensconced in a dumpy little golf cart absurdly shaped like a huge football helmet, onto the field during a game, everything winds up during spring break in Mexico, where the campus kingpin in the drug distribution scheme is revealed and the guys wind up dangling from the helicopter in which Ghost is escaping—a scene that, after the introductory chase sequence, bookends things nicely.

There are bits of “22 Jump Street” that don’t work, sometimes simply because of bad timing—a running gag about Schmidt being called Maya Angelou might make one cringe in view of the poet’s recent death, and a jocular mention of Tracy Morgan early on might make you feel queasy, too. But overall the movie is consistently amusing and sometimes hilarious. A good deal of the credit has to go to writer Michael Bacall, of course—this time around working with Oren Uziel and Rodney Rothman rather than solo—but no one should discount the contribution of directors Phil Lord and Christopher Miller, who have upped their game considerably since the first installment and bring to the party much of the good-natured zaniness that made their “Lego Movie” such a happy surprise. They even manage to put their expertise at animation to good use in drug-fueled hallucination sequence that also employs a split screen for comic effect.

It’s impossible to imagine the movie, though, without Hill and Tatum, who seem more and more like an inspired pairing. But again in a reversal from the first movie, except for a few flamboyant moments like an extemporaneous bit of slam poetry (and an inept bit of role-playing in the first scene with Stormare), Hill is the more subdued of the two, going into a funk when his partner appears to dump him for a life of frat and football. Tatum, on the other hand, comes on strong in both the comedy and action departments, a hunky Laurel to Hill’s Hardy. And both manage the absurdly soap-operatic moments in which they talk about the possibility of “investigating other people” and having an “open investigation” with a measure of loopy poignancy that actually helps to keep the picture from becoming a live-action cartoon.

Ice Cube again comes across as a force of nature as their volcanic captain, Stormare brings a nice touch of wryness to the villainous Ghost, both Russell and Stevens are engaging and likable, and Offerman brings his patented grouchiness to the long-suffering chief. Adding strong support to the ensemble are Keith and Kenny Lucas as zonked-out twin dorm mates of the cops and Jillian Bell as Maya’s grumpy roommate, who overlooks no opportunity to comment on Doug/Schmidt’s blatantly advanced age. Plenty of guest stars stop by unannounced for cameos, including a couple from the old TV show and two from the first movie. Most of these bits are little more than throwaways, and some (like that featuring the surprise returnees from the previous flick) serve only to reinforce how much better this sequel is, but the one in the closing credits montage is a doozy. The technical credits are all fine, with glossy cinematography by Barry Peterson and crisp editing by David Rennie and Keith Brachmann.

Despite the inside jokes, a “23 Jump Street” is probably already in the planning stages, and if it can match this installment, a welcome mat would be in order at that address.