Get ready for another fashion flashback! On Season 4 of Mad Men, the wardrobes of our favorite retro characters will reflect the influence of the mod fashion movement that defined 1964. But don't expect to see Betty in a miniskirt or Joan shedding her foundation garments. "It's like anybody's life, you add pieces to your closet but you're not changing your whole style with every trend," says the show's costume designer, Janie Bryant. While Peggy's clothes represent her independence and Betty's new life brings with it a Jackie O-inspired silhouette, Don's personal and professional struggles are mirrored through a darker color palette and Joan proves that she knows how to accentuate her positive assets no matter what changes in the world of fashion. Click through our gallery for a sneak peek of what they'll be wearing on Season 4 of Mad Men, premiering July 25 on AMC.