And God said to Joan...

Call it omniscience, luck, or simple self-preservation: On the day before her once highly popular TV series ''Joan of Arcadia" got the ax recently, 22-year-old Amber Tamblyn was in Boston beginning a press tour for her first major movie role.

As Tibby in ''The Sisterhood of the Traveling Pants" -- not to be confused with ''Divine Secrets of the Ya-Ya Sisterhood," ''Tha Sistahood," or ''Boyz N the Hood" -- Tamblyn gets to play the sarcastic, self-alienated discount-store clerk of Ann Brashares's best-selling novel. The likable two-hour movie, which was directed by Ken Kwapis and opens Wednesday, can be described as quality soda pop with better than average fizz. Fans will be happy that the tragicomic screenplay, adapted by Delia Ephron and Elizabeth Chandler, is mostly faithful to Brashares's 2001 book, which went on to spawn a franchise of follow-up novels, scrapbooks, and other products.

Tamblyn, who last year garnered an Emmy nomination for perfecting the family-friendly wisecracking suburban teen, does roughly the same thing in her latest big-screen effort, except with a grumpier attitude and less fashion sense. The two characters are close enough to imagine meeting: ''I think Joan would think Tibby is self-indulgent and rude," Tamblyn speculates with a grin. ''And I think Tibby would think Joan is obsessive, compulsive, neurotic, and bipolar."

Maybe not the traits one looks for in a best friend, but as a creative way to make a Hollywood living, how lucky can one young actress get?

Tamblyn must seem especially fortunate to Christine Sullivan's sixth grade class at Abington's Center School, which sent one student representative and a pile of questions written on index cards to this interview in a Boston hotel suite. So it's not surprising that the number one thing these kids want to know is: Just how much does a young actress make these days, anyway?

The performer squirms and fumbles good-naturedly when confronted with the question. ''More than minimum wage?" she finally offers with a shrug.

She's more successful answering kid queries such as ''What was your favorite grade?" (''Tenth; I really liked geometry. And no, I don't use it today.") and ''What would you be if you had one night to be whatever you want?" (''I'd want to be France; the whole country -- all the buildings, all the people -- France! I don't even know if that's true, but that's what I'm saying.") Most impressive is the attentive and regular way she interacts with her student interviewer; after a few minutes of watching the affable star in action, her canvas black sneakers tucked under her jeans while she fidgets in a stiff hotel chair, it isn't hard to understand her casual appeal to this demographic, or the karma that seems to keep landing her on her feet.

At minimum, Tamblyn does seem blessed by the casting gods. But then it also helps if you're the daughter of actor Russ Tamblyn (''West Side Story," ''Twin Peaks"), the goddaughter of actor Dean Stockwell (''Quantum Leap"), and the product of theatrical training that began before you could tie your shoes. When she was only 11, little Amber landed the role of Emily Quartermaine on the daytime soap opera ''General Hospital," a gig that was supposed to last three months but ran seven years. She's done big parts in little movies (''Rebellious"), little parts in big movies (''The Ring"), and guest shots on TV shows such as ''Boston Public" and ''Buffy the Vampire Slayer."

Her first big break was winning the lead in ''Joan of Arcadia," and now with that show gone after just two seasons, she's free to put all her energies into ''Traveling Pants" and an unrelated book of poetry (''Free Stallion") due out in October.

More on the poetry later.

Tamblyn's current movie costars demand mentioning first -- because they are Alexis Bledel (''Tuck Everlasting" and TV's ''Gilmore Girls"), America Ferrera (''Real Women Have Curves"), and newcomer Blake Lively, and because they apparently formed an instant sisterhood of their own on the set.

''Ohmygosh, the dynamic. You mean the madness? The craziness? The pranks?," Tamblyn says with a laugh. She fondly recalls their efforts to convince entertainment reporters that Ferrera was engaged to actor Vince Vaughn, and she smiles over the night that shy Bledel was persuaded to enter a public break-dancing contest. ''She lost, but she got down and did some moves," reports Tamblyn. ''It was pretty cool."

For Lively, whose first-ever acting job is this performance as the statuesque, confident, athletic Bridget, the cast camaraderie and creative leeway allowed by their director may have ruined her for any future assignments in showbiz. ''Ohmygosh, we don't even know when they called action and when they called cut," she says. ''We were just talking at all times."

When they weren't saying ''ohmygosh," they were in one another's trailers, choreographing dances to Vanilla Ice tunes. ''I don't know why," says Lively, a high school senior, with a shrug. ''We were like, off our rockers. I mean we had so much fun it shouldn't be allowed. And Ken [Kwapis] is an amazing man to put up with us; he had so much patience."

Kwapis, producer and director of television fare such as ''Freaks and Geeks," ''The Larry Sanders Show," and NBC's version of ''The Office," knows the value of giving actors room to relate organically. ''When they were together, it was important to let them be," he explains by telephone. ''They did sort of create a great cacophony, but I feel like the real music of this film is the sound of their voices together."

Brashares's original conceit for the ''Traveling Pants" story is as simple as it is brilliant: Four friends find a pair of blue jeans that magically fit each one of them like a dream, even though none of them has the same body type or taste in clothes. The teens, whose moms all met in a prenatal aerobics class, agree to share the jeans -- each girl gets them for one week at a time -- while they spend the summer in different locations. There are rules (never double cuff, never launder) and maybe the most magical thing is that each girl fulfills her promise to part with the pants on schedule.

Cranky Tibby stays home in Bethesda, filming a documentary about pathetic local lives; Bridget attends a soccer camp in Mexico; Lena (Bledel) visits her grandparents in Greece; and Carmen (Ferrera) goes to South Carolina to reconnect with her estranged dad. Since jeans are a universal symbol of female insecurity (as in, ''Seriously, does my butt look OK in these?"), each wearer's personal defects are not magically erased but exposed. The film deals with grief, anger, lust, love, depression, and countless other emotions; denim is the fabric that many critical moments play out in, but it's only the most superficial part of what knits these stories together. The thing Tamblyn liked most about the script was its shared feminine strengths.

''Unlike a lot of teen films, [''Traveling Pants"] didn't stereotype women," the actress explains. ''A lot of films make teenage girls victims, people who can't defend themselves and who have to fight each other to have any kind of an identity. I feel like this film doesn't do that and the book didn't do that, and I think that's encouraging."

As mentioned, Tamblyn is a fan of poetry, but she isn't a fan of the showbiz machine. On her website (www.amtam.com), this diamond-abstaining, Ani DiFranco-listening vegetarian who goes by the alias ''darkestrose" cautions fans about the pitfalls of fame. Her upcoming book will expose some of Hollywood's less flattering inside workings, she says, and her passion for slam poetry (''it's like rapping for white kids," she enthuses) should make readings pretty lively when she tours to promote ''Free Stallion" in the fall.

For now, you can read some of her poems online. One, titled ''Clouds," is even brief enough to include here in its entirety: My mother said my shadow often looked like a cloud./ I said I often felt like one.

And God said to Amber: ''Be glad. Clouds are one of my better creations."

Janice Page can be reached at jpage22@hotmail.com.