Humans, like other organisms, modify their environment, but the degree to which humans have become capable of modifying their environment is unmatched by any other living organism on earth. One would be hard pressed to find today any environment in which human agency has not had a direct, indirect, or inadvertent impact, whether through land use and land cover change, via the introduction of alien species, or due to industrialization and the alteration of biogeochemical cycles. The introduction of alien species is one aspect of human agency that is dealt with in the collection of articles that follows. The other aspect of human agency dealt with in this collection of articles is a byproduct of industrialization, namely environmental pollution.