The previous chapter suggests that environmental problems expand in number and seriousness as a consequence of economic growth. Certain environmental conditions, such as urban smoke pollution, may worsen for a time and then disappear, but many environmental problems don’t, and new ones emerge along with new forms of economic activity. How can the proposition be substantiated that environmental problems are cumulative because of the cumulative addition of new kinds of economic activity? To answer this question is the central goal of this chapter.