An Exclusive Look at the Making of Get On Up

He was a sweating, shrieking, superbad sex machine, the man who rose from picking cotton, shining shoes, and dancing for pennies in Augusta, Georgia, to become the founding father of funk. Bringing James Brown's dynamism back to life in Get On Up, the first-ever film about the musician, was no small task for actor Chadwick Boseman (who played Jackie Robinson in 42). "I was petrified," says the 37-year-old. "This is James Brown we're talking about! You can't get that story wrong."

Boseman knew he'd have to pay the cost to be the boss: He had only a couple of months to master Brown's smooth moves and bravado before filming began in Natchez and Jackson, Mississippi. To learn about the icon's life—the good, the bad, the ugly—Boseman and director Tate Taylor (The Help) road-tripped through Georgia and South Carolina with Brown's albums as their soundtrack, visiting his hometown, family, and ex-wives. "We needed to know every single thing there was to know about James," Taylor says. "His life was as complex as his music—and his dance moves."

Along the way, the pair met Brown's grandson Jason, who joined the crew as a production assistant. "There were moments," Taylor says, "when Jason would watch Chad and go, 'Wow, this is unreal'"—a testament to Boseman's obsession with getting (and staying) in character. "It took me two months once I got home to be myself again," Boseman says. He wasn't the only one who couldn't shake the feeling. "After we wrapped, the cast and crew all stuck around for a few days," says Taylor. "Once you're in James Brown's world, you don't really want to leave."

To prepare for his lead role, Chadwick Boseman read biographies of Brown, loaded up his iPod with Brown's albums, and watched footage of interviews and performances to master Brown's gravelly drawl. While a majority of the singing scenes feature Brown's original recordings, Boseman filled the gaps with his own vocals.

The film was a reunion for Octavia Spencer and director Tate Taylor, who worked together on The Help. "Tate knows how to spin a yarn," Spencer says, "but he was dedicated to telling this prolific man's story in both an artful and truthful way." Spencer plays Aunt Honey, who took Brown into her Georgia home—which doubled as a brothel—when he was around 5. Of all the period costumes Spencer wears throughout the film, she especially loved putting on Honey's formfitting pink dress (above). "When I saw this—honey! It made me feel beautiful and womanly," she says. "Perfect for my character: She's enterprising—and she's nobody's help."

Though Jill Scott, who plays Brown's second wife, Deedee, spoke with Deedee's grandson to learn what made her tick, the singer also let her imagination run wild. "I decided to act as unabashedly in love with James as I believe Deedee was," she says. "From the way I drank a glass of water to how I walked toward him, I consumed myself with passion for this man. After we stopped filming, I was in mourning. I think I actually fell in love with him!"

"In this scene, James is backstage, hearing the crowd chant his name as he thinks back on his life," Taylor says. "I'm explaining to Chadwick the different memories I want to see reflected in his face. You won't believe how this guy transforms into James Brown. This is his career-defining moment."

Boseman, who'd never had professional dance training, worked with a choreographer every day for six weeks—and kept practicing between takes. "I thought I was in shape," he says, "but the mashed potato used body parts I didn't know I had." The souvenir Boseman made sure to snag? A few pairs of dancing shoes.

Wig consultant Robert Stevenson, who looked to archival photographs for inspiration, says the toughest part of his job was making Boseman's hair stay put: "A wig isn't meant for someone jumping around like a wild man."

Stylist Carla Farmer referenced vintage Jet magazines and Motown stars like the Supremes to create hairdos for the women in the cast, including Tika Sumpter (above) and Aunjanue Ellis, who play singers in Brown's revue, and Viola Davis, who portrays his mother. For authenticity, Farmer stuck to an old-school styling technique: "Women of that time used marcel irons, which are stove heated," she says, "so I did, too. You really can tell the difference between hair done with a stove iron versus an electric one!"

Costume designer Sharen Davis (Dreamgirls, Ray, The Help) had to capture Brown's iconic flashy style across more than three decades—which explains Boseman's 50-plus wardrobe changes. After sketching costume ideas, Davis and her team scoured the Web and thrift shops for vintage finds. "I strayed a little beyond the confines of a biopic," she says, "by choosing modern fabrics and tweaking Brown's tight silhouettes. He was only 5'6", so to create the illusion that Chad, who's six feet, was shorter, I had to loosen his pants."