These croutons are made with French bread. The loaf I used was a baguette from Trader Joe's. Sourdough is another solid choice for a good, hearty crouton, but honestly most breads will do. I've even made croutons with leftover bagels before! The only breads I'd avoid are super delicate or soft breads. For example, I don't think a croissant crouton would turn out very well and don't do something lame like Wonder sandwich bread.