Aspiration of and asphyxiation from small objects is a well-known danger to young infants and children. At present, there are three different federal regulations that address this problem, by specifying different dimensions of height, width, and length. The Small Parts Regulation, which affects toy size, is the least stringent and is being challenged. The anatomic and physiologic concepts behind these important regulations are analyzed and discussed. The idea of a single generic standard is also reviewed.