Garnerís research for the role of Jenna, included hanging out with 13-year-olds and trying to remember what was special ó and not so special ó about that age. ìLuckily, I have this really good friend, Madeline Sprung Keyser, who was 12 at the time and weíve been friends for five or six years,î says Garner. ìEvery now and then she will react to a situation like an adolescent and remind me that she's everything at once ó a grown-up child. A kid of 13 can seem like an adult, but that can be deceptive. You always have to remember they are also incredibly vulnerable, skittish and childlike. Finding that balance was challenging.î

Another aspect of the character Garner researched was how 13-year-olds relate to one another. For this she turned to producers Arkoff Roth and Arnold, ìborrowingî their teen daughters Hannah and Julia for a sleepover. ìHannah and Julia invited some of their friends over and we all spent the night together. I stayed up as late as I could, which I have to admit wasnít very late. I did try to rouse myself around 4 a.m. because I knew some really good stuff had to be going on. I dragged myself into the kitchen where they were all talking. I tried with all my might to pay attention and stay awake. Unfortunately, I donít remember much of what happened then. Hannah and Julia later told me that I stumbled in, made a símore, ate it and went back to bed. Oh, to really be 13 again,î she laughs.

Despite her best efforts to bond with teenagers, there were some places Garner drew the line, especially when it came to the sleeping arrangements. Faced with the prospect of nodding off in a sleeping bag, Garner commandeered the couch. ìI told them, ëHey, I am 30 years old. Iím pulling rank. I get the couch and I am going to bed right now.íî

In the movie, Jenna Rink is lucky enough to have every teenagerís fondest dream come true. She gets to skip the challenges of adolescence and find herself already grown up enjoying the fruits of adulthood. During the rehearsal period, the 13 Going on 30 acting ensemble bonded, sharing their own personal stories about the agonies and joys of growing up. ìWe all remembered how terrified we were of all that lay ahead for us,î says Garner, to which Greer adds, ìWe all related to how badly we wanted to be on our own at that age and not have anyone tell us what to do ó even though we knew we werenít really ready yet.î

The cast members also confessed some of their own wishes and dreams as teenagers. ìI was in a very awkward stage for a long time,î says Garner. ìI played in the marching band. I didnít wear cool clothes ever and I wore huge glasses. I just wanted to grow up and be able to put one foot in front of the other and carry on a proper conversation. Oh, and to wear contact lenses,î she laughs. ìI really wanted contacts.î

Ruffalo admits, ìLike any teenager, I was always wishing I was someone else and somewhere else. Now, I look back at pictures of myself and think, ëI wasnít that bad.íî

For Greer, her teenage years were marked by the kind of torturous anxiety that only peer pressure can engender. ìAt the time I didnít think Iíd ever fit in or find a place where I belonged,î she says. ìWhen youíre a kid you think itís really important to hang with the cool people at your school. Then when you grow up, you realize it doesnít matter at all. They donít even end up being your friends. You have all new friends ó thank goodness.î

Serkis remembers that at 13 all he wanted was the chance to see Steven Spielbergís classic Jaws. ìI was furious that my older sister could see it and I couldnít. So I borrowed a pair of shoe lifts and my sisterís mascara to fill in the tiny bit of moustache hair I had and tried to pass myself off as older to get into the theater. It didnít work.î

A touchstone of their common experience is evident in the filmís ìThrillerî dance sequence ó a nod to Jennaís childhood and the 1980s. It takes place at a hip New York party for Jennaís Poise magazine at which she innocently tries to liven things up, with a group of people who have apparently forgotten how to have fun. When Jenna starts to dance, however, her guests drop their poses and soon everybodyís dancing.

ìI had only one cassette tape growing up and it was ëThriller,íî says Garner. ìSo getting to do that dance, to rehearse it and have all the back-up dancers was seriously one of the most fun experiences I have ever had.î

Ruffalo agrees, though when it came time to actually dance, he suffered from a bit of stage fright at first. ìThat was my youth,î he recalls. ìëThrillerí was the tape that everyone passed around. But I was really nervous about the dance because I really donít dance. We had to take lessons. I wound up having a very good time.î

Greer also had a good time during the dance rehearsals. ìIt was really enjoyable to work with the choreographer and learn the routine,î she says. ì It was so cool to be part of a great big dance number in a movie. It was also tougher than it looks. My feet hurt for three days.î

Like Ruffalo, Serkis was a bit apprehensive about the dance number ó actually, ìterrifiedî is a better word, he says. ìI had no idea it was going to be a full-fledged routine. I got a call in London, where I live, saying they wanted me to do a moonwalk. So I spent ages with a choreographer. When I arrived on set the first day of dance rehearsals it seemed as if everyone knew the routine very well. I was terribly frightened. Fortunately, we were allowed to fall in and out of it, just as people who are remembering an old dance would normally do.î

The spirit of the dance number proved to be infectious. Even producer Matthews got into the swing of it. Dusting off her 80s dance shoes, she stepped in front of the camera and let her hair down. ìLike everyone else, I was obsessed with ìThriller.í I stayed up until midnight when it premiered on ABC. I recorded it on my Beta deck and memorized every move. When we started rehearsing, all the moves came back. They were ingrained in my memory.î

For Winick, the challenge of the dance sequence was to harness the actorsí energy and make the scene build organically to serve the story. ìI didnít want it to feel like a music video. I wanted it to work dramatically. As good as the dancing is, the reason the scene works is because itís plot oriented. Jenna is saving the party the way a 13-year-old would, not an adult.îÝ

There are other 80s references in the movie ó from pop icons like Madonna, Rick Springfield and Pat Benatar, to slang like ìgrodyî and ìgag me with a spoon.î Since most of the actors grew up in that period, ìit was super fun,î says Greer. ìIíd forgotten a lot of it, but after awhile it all came backî

In the film, Garner makes use of her experience with physical action ó only this time itís in the service of comedy. ìI think thereís a huge correlation between physical action and physical comedy,î she says. ìItís all about being used to being in your body and not being afraid to go for it.î

Her invaluable partner in the transition to physical comedy was her director, she says, who allowed her free rein, but always kept her focused through his keen attention to detail. ìI donít know if itís because of his background in independent films, but Gary is better with story than anyone Iíve ever worked with,î she says. ìHe was always aware of the logic of this strange little world weíd created for the character and the reality of what would happen to her from moment to moment. There was never a second when I didnít feel like he elevated what I was doing.î

Greer was also taken with Winickís highly personal style of directing, again a product of his background in independent film. ìHe was never back at the monitor or hidden behind 14 assistants,î she says. ìHe was right there next to the camera, watching us, talking to us. And I came to trust him to that degree that I knew he wouldnít stop until he had gotten what he wanted out of us. He knew what he wanted and was able to tell us what it was.î

The producers were also enthused about Winickís team-player approach as well as the personal insights he brought to the project. ìGary understands women very, very well,î says Arnold, ìand heís dogged about the things he believes in. He always remains true to himself, and yet at the same time he is unbelievably collaborative. Heís eager for input and was open to all our ideas and gave them the weight and respect they deserved.î

Adds Matthews, ìHe really cares about being truthful to the theme and that the audience really understands Jennaís journey. Gary had a strong sense of both the comedic elements and the truth of the story. And that combination is priceless. It brought wonderful levels of subtlety to the film.î

Coming from the independent world of digital-video and minimal crews, Winickís first foray into Hollywood-style filmmaking initially took him aback. ìI think he was a bit shocked when he walked onto set the first day and there were 100 people there instead of just four,î laughs Arkoff Roth.

Winick admits that the sheer size of the production took some getting used to. ìI came in thinking that dealing with such a large crew might be frustrating, especially since I was able to accomplish a great deal on Tadpole in 12 days with a digital-video camera and just a few people. On 13 Going on 30, I was suddenly dealing with more than 100 crew people at a time. Once I got to know everybodyís names it was great to have. There were some, like the men and women down on the street controlling that traffic, who I hadnít even met yet. But what was gratifying was the level of experience and professionalism. They thought of everything. Nothing ever got by them. And thatís very comforting for a director.î Ý

A native New Yorker, Winick was also happy that 13 Going on 30 was set in New York ó and then surprised to learn that all the interiors would be shot in Los Angeles. ìI am a New Yorker and want to make all my movies in New York. So picking a project set in New York was a big plus for me. So I was amused when I found out most of it would be done in L.A. In the end, however, it was a great experience to shoot in L.A. and I got to shoot 17 days in New York. And by the time we got to New York to film the exteriors, I was really well prepared and very comfortable with the crew.î

Garner was also accustomed to shooting in New York and was thankful for her experience on ìAlias,î which better prepared her for the crowds that formed around the locations everywhere she went. ìOne day we were in the middle of Manhattan and there were hundreds of people watching from across the street. I had to come though some revolving doors and freak out ó to jump up and down waving my hands wildly in the air with all these people watching. They really had no idea what I was doing or why I was doing it. And there were all these paparazzi taking pictures. It was a bit intimidating. Fortunately, I was familiar with acting in public because of ìAlias,î which made it somewhat easier to pull off.î