This is an animated film by John and Faith Hubley. The dialog is by their daughters Georgia and Emily. The former of these daughters later went on to co-found Yo La Tengo (shown up a few times on my FR10 lists.) What's cool is that they seem to let the animation flow out of what the girls are saying, leading it to places it might not have gone.
It carries a sixties air with it, even though you won't mistake it for the two giants of sixties animation. (Yellow Submarine and The Jetsons of course.)