The tiny ones are often better climbers...they are light so it is easier for them to pull their weight upI agree with the others who have said either put him in a playpen in the room with you or on a mat/cot in the room with you until he learns to stay put. Also, some playpens are bigger with higher sides than others...I just bought one that is smaller and had to give it to the youngest/least likely to learn to climb out. Is it possible that the playpen he is in is a bit smaller? Maybe you could swap it for a larger one?