As Mad Men barrels into the sixties, no character has evolved more than Peggy Olson. As played by Elisabeth Moss, Peggy was a buttoned-up, Brooklyn-born-and-bred 20-year-old Catholic secretary in season one. Now it’s 1965 and she’s a pot-smoking, stripteasing, bohemian-befriending senior copywriter—and sort of, kind of, a heroine. How’d that happen? As this last episode dramatically rejiggers her arc on the series (spoilers, ahoy!), we look back at how far she’s come.