Colbi prefers the grass, but when its like -25 degrees outside and a huge amount of snow in the backyard, or if its raining (we get HUGE puddles in our backyard and she comes in all muddy and soaking wet), she goes on the driveway. But when it's nice out we always bring her in the backyard. If she does go on the driveway though we pick it up right away. Don't want anyone coming to our house and seeing doggie poop all over the place.