This doll is by Mattel, and either from 1971-1972, I think. She's a friend of Barbie, a Jamie sculpt, and was a Sears department store exclusive. She was a "walking" body, and it still works. When you make her legs walk, her arms swing in the opposite direction, and her head tilts.
She also was available in blonde and brunette. And I believe she's closer to Midge in size than Barbie. But super sweet!
She's so cute. You can see more shots of her on my Flickr photostream.