For the purposes of this paper, a staple is a product with a large natural resource content. Some part of its fabrication must take place at the spot, even if only in the trivial sense of seizing it away from nature. This paper finds that the staple theory though not perfect is the most appropriate context in which to evaluate the process of Canadian economic development. As such, it makes an enormous contribution to the study of Canadian economic history. This point will be developed by looking at the evolution of the staple theory,and by its application to the well-known historical facts of Canadian economic development.