Mary Tyler Moore was permitted to wear pants in only "one scene per episode"

From a 1995 interview:

Moore: I mean, society's expectations at that point still said, hey, wait a minute, lady, you only go so far here. But I think we broke new ground, and that was helped by my insistence on wearing pants, you know, jeans and capri pants at the time because I said I've seen all the other actresses and they're always running the vacuum in these little flowered frocks with high heels on, and I don't do that. And I don't know any of my friends who do that. So why don't we try to make this real? And I'll dress on the show the way I do in real life.

GROSS: But it wasn't that easy. The sponsors were afraid you'd look brazen.