Very sturdy! Even my 10 year old and 13 year old play with their 2 year old brother on it! My 2 year is a climber and kept climbing one EVERYTHING....so I wanted to get him something that he could use indoor and outdoor when we can't go to the park. He is absolutely in love with it! We put a pillow and blanket underneath and it's like his own little rest area! I highly recommend this play climber!