The book is an introduction to University Ecotoxicology for under degree students attending Environmental Science related courses. It was organized into 14 chapters, with the first section lecturing a historical overview of the discipline, the major environmental pollutants, and the uptake and bioaccumulation of those contaminants. Then, the second and third sections addressing the toxic effects of pollutants at organism and ecological levels respectively. Finally, the fourth section presenting methodological tools such as toxicity bioassays, biomarkers of environmental pollution, and the ecological risk assessment. Chapters were structured with the issue theoretical introduction, self-case examples, and practice methodological tools. Each chapter was written by specialists in the subject from different universities of Argentina.