In the early 20th century, proponents of the so-called "social efficiency movement" in the United States tried to apply methods and concepts for enhancing efficiency in industrial production to the organization of teaching and learning processes. This included the formulation of "educational standards" analogous to industrial standards. While the concept of educational standards now has advocates in many parts of the world, today's rationales for standards-based reform differ strongly from those put forward then. In a series of "snapshots", this article traces the changes in the ways educational standards and standards-based reform were legitimated over the course of the 20th century. It focuses on the United States, but as standards-based reform has become a truly global phenomenon, it also discusses educational standards as they have been implemented in Sweden.