Our world is overpopulated with people and they're using up too much of the earth's limited resources. This fact lies outside of the typical activist's perspective and doesn't fit into society's dominant anthropocentric worldview. When it comes to our use of natural resources, we are taught to consider issues related to consumption such as energy efficiency and recycling. However, the number of people - and how fast that number is growing - is a more important factor. More people consume more resources, need more services, produce more waste, and create more world conflict as resources diminish. Working on downstream issues, such as saving the environment, feeding the hungry, and ending homelessness, is noble but ineffective and inefficient without also working to solve the primary cause of these and other important issues. In Move Upstream: A Call to Solve Overpopulation, Karen Shragg challenges social and environmental activists to stop working downstream and take the problem of overpopulation seriously. She also provides compassionate ideas to solve the problem.