Easy to assemble. My cat is medium and slender (weighs 14 lbs), but he cannot fit in the second level cubby hole and hangs over the 3rd level cat bed-type chair with side supports. He doesn't use the ladder, the highest platform, the scratch posts, the hanging toys and ropes. I have been giving him cat treats, catnip, his favorite blanket on the top platform. He will go up and get the treats and promptly come back down. You just can never really be for sure that you cat will adapt to things like this.