I have two cats. I think they are both using it, but we have one box with clay litter that is still being used so I can't tell. However, it has only been a few weeks and I LOVE how light the litter is and how non-dusty it is. That it is more ecologically sound is also great. Some people said it gets dragged around a bit more--but I have found the opposite. The clay litter I find more of outside the boxes