Despite some conspicuous stumbles (e.g., the “Cars” series, “The Good Dinosaur”), many viewers regard Pixar product as the gold standard in animated family fare, and the “Toy Story” trilogy (1995-2010) near the top of the list in terms of heart and humor. So good was the last of the three that one critic, who shall remain nameless, noted that it left room for another installment but asked, “Why court ruining a series that’s gone so well until now?”

However right he might have been about the possibility of a letdown, his worries were misplaced. “Toy Story 4” does the franchise proud. Every bit as lovable as the first three films, its mixture of rambunctious fun and sentimental schmaltz is utterly irresistible. In a summer of sequels that have too often proven dismal disappointments, it’s an oasis in a cinematic desert, a combination of the familiar and the new that makes for an instant classic.

The stage is immediately set with the stable of toys’ new owner, little Bonnie (voiced by Madeleine McGraw) fearful about having to go off to kindergarten. Woody (voiced again by Tom Hanks), who may no longer be her favorite but remains as loyal as ever, decides to sneak into her backpack as a protector on orientation day, and a good thing he does: he provides her with stuff from a trash can that enables her to fashion a toy of her own—a plastic fork to which she attaches some pipe cleaners and googly eyes, pronouncing the result Forky (Tom Hale).

Forky, however, rejects the idea of being a toy and wants to return to the trash heap. One of the running gags in the picture will be Woody’s incessant efforts to prevent him from committing forkicide and teaching him what it means to be a toy.

That happens during a pre-school road trip the family takes to the tourist town of Grand Basin, during which Forky’s latest escape attempt leaves him and Woody on the side of the highway while the RV rolls on, the other toys like Buzz Lightyear (Tim Allen) concerned about their friends. When the missing duo finally hoofs it to their destination, Woody is distracted by a memento of a long-lost friend in a secondhand goods store window—the lamp on whose base porcelain Bo Peep (Annie Potts) and her gaggle of sheep had once stood. When no longer needed to serve as a nightlight, it was given away—and Bo Peep told Woody it was time for her to go as part of the natural order of kids growing up.

Much of what follows will play out in the store and the carnival across the street from it. Woody and Forky sneak into the place, run by an elderly lady (June Squibb), in search of Bo Peep, but what they encounter instead is Gabby Gabby (Christina Hendricks), a pull-string doll desperate to secure a properly functioning voicebox—like Woody’s—which she’s sure will make her a cinch to catch the eye of the owner’s granddaughter Harmony (Lila Sage Bromley). And she has henchmen in the form of a bunch of sinister ventriloquist’s dummies who might have stepped from the pages of “Goosebumps.”

The upshot in the ensuing action is that Woody escapes but Forky doesn’t, and to rescue him Woody will seek the help of Bo Peep, who’s been living a life of independence on the outside with some new friends (most notably tiny Giggles McDimples, voiced by Ally Maki). She’ll enlist one of her old store buddies, motorcycle daredevil Duke Kaboom (Keanu Reeves), as well.

Meanwhile Buzz leaves the RV in search of Woody, and convinces two initially hostile plush toys from the carnival’s prize booth, Ducky (Keegan-Michael Key) and Bunny (Jordan Peele), to join in the caper. Many gambits, chases, last-second escapes and turns of fortune follow, with the screenplay by Andrew Stanton and Stephany Folsom inventive in devising the action sequences and clever in juxtaposing them with moments of sweetness and poignancy, as well as in creating new characters—like Forky—that prove as ingratiating as the old ones. And while remaining true to the series’ messages about loyalty and commitment, the scripters also manage to close things out with an ending that’s satisfying even as it invites a few sniffles.

As might be expected from this source, the animation is exceptional, and the voice work equally so. Hanks and Allen reprise their roles with their customary élan, and Potts returns as an energized symbol of girl power, abetted by Maki’s hyperactive sidekick.

And while the other old characters are mostly reduced to cameos, the new ones prove ready to take center stage. Hendricks manages to bring a nice degree of nuance to Gabby Gabby, who’s desperate to have a relationship with a child (shades of the recent bomb “Ugly Dolls,” which handled the idea much less successfully), Key and Peele make an amiable grousing pair, and Reeves is a hoot as the arrogant Kaboom. The breakout star, however, will certainly be Hale’s goofy Forky, whose wayward efforts to return to the wastebasket will delight kids and adults alike. The score by Randy Newman, which makes use of some favorites as well as offering a few new treats, is another plus.

“Toy Story 4” represents a directorial debut for Cooley and a screenwriting one for Folsom (though she’s paired with veteran Stanton). If this is part of a passing of the torch at Pixar, it’s wound up in good hands.