You can't kneel on the green to see how solid it is. Rule 3: If kneeling on the green leaves causes dents in the surface, fix the dents before going on to the next hole. Aside from that, you can kneel on the green. It's even allowed to putt while kneeling, but the USGA advises against it. They say it interferes with your sense of distance and angle, which could affect your stance and grip. The main reason people don't kneel on the green is because they might get stuck. If the ground isn't firm enough, you could get stuck and hurt yourself. But there's no rule that says you have to kneel on the green. You can stand up while putting if you want to. The only people who should be kneeling are those with physical limitations such as short legs or arthritis. Otherwise, you're free to use whatever position allows you to putt the best shot.