This publication addresses the remediation of non-urban terrestrial and freshwater ecosystems including agricultural, forest and aquatic environments contaminated with radionuclides by radiation accidents, radiological incidents and other past activities. Associated social, ethical and economic considerations are also presented. The book describes modern decision aiding technologies and environmental decision support systems for remediation planning and optimization. Several case studies, demonstrating remediation success (radiation and radiological accidents, nuclear test sites, etc.) are presented and evaluated. The publication considers only remediation strategies and management options that are relevant for existing exposure situations. Management options (countermeasures) for pre-deposition and early phases after emergencies are the subject of other IAEA publications.