He is using the Purina litter called Second Nature. We just got little Gnocchi our Papillon puppy a week ago, and he is already using his litter box. When he is in this bathroom he is now 100% successful every time. He is now 9 weeks old. This is our first puppy and we are so surprised at how great Crate Training is. Gnocchi will be a litter box dog for his entire life because we dont have a yard. Update 3=4=09 he is now 4 months old and is still using his litter box. He has 3 boxes around the house. He misses on purpose though so we use puppy pads underneath, and only treat him when he is fully inside the box.