Geochemical characterization of tailings forms an essential component of understanding the potential environmental risks and liabilities associated with tailings disposal and how to prevent, minimize, or mitigate any environmental impacts. The environmental issues typically identified as being of most concern are metal leaching and acid rock drainage, and will be the focus of this presentation. The reasons for, approach to, and timing of tailings geochemical characterization will be introduced and illustrated using case studies. Resources will be provided for further study.