Tonight as I was playing with Calvin, he was sitting against my legs playing with some toys for several minutes before I realized he was sitting up on his own. I pulled back to see how long he could stay up by himself, and with absolutely no help he stayed up for 11 minutes! After that, he was a pro. He was sitting up on his own playing with toys and was even able to catch himself when he lost his balance. Eventually he got tired of sitting up and toppled over, but it was amazing. Until this morning he hadn't shown any inclination to balance on his own, and then all of a sudden this evening he acts like he has been doing it for weeks. We are so proud of him!