The rule: Use “Me.”

Incorrect version: “She went to the store with Sally and I.”
Correct version: She went to the store with Sally and me.

Incorrect version: “Between you and I…”
Correct version: “Between you and me…”

“I tell people to imagine the sentence with only one person because that usually makes the pronoun choice clear,” says Mignon Fogarty, creator and host of the Grammar Girl podcaston the Quick and Dirty Tips network. So think of it this way: You wouldn’t say, “She went to the store with I,” right? “Adding Sally doesn’t change anything,” Fogarty says.