This thesis seeks to analyze what would have to change in American discussions of global environmental sustainability for population growth to assume its rightful place in the discussion. The amount of carbon that people consume times the number of consumers determines the total carbon emissions and thus environmental impact, yet most environmentalists avoid any mention of population growth. I examine the common sources of opposition—religious, feminist, capitalist, ethical, and even environmental—to understand what specific element of population stabilization each group reacts against and whether there are ways to address those concerns while still discussing population growth in environmental terms. To do this, I conducted informational interviews with people in the population and/or environment movement, observed a population organization and did archival research there, and read population-ethics theory. I suggest that sustainability discussions can include population growth, within certain important bounds, and in doing so, create the space for more effective policy.