In the 1970s, considerable interest arose into the study of multi-output firms and industries. However, this literature did not seem to be aware of the contribution that von Stackelberg made to the issue almost half a century earlier. This paper outlines von Stackelberg's contribution to the theory of costs under joint production. It critically assesses the place of his contribution in the modern history of the theory of joint production and it suggests an answer to the question of why von Stackelberg's theory of joint production fell into oblivion and even contributed to the abandonment of the issue for decades.