The third edition of the handbook Strategische Umweltpruefung (SUP, Strategic Environmental Assessment) has been substantially restructured, reworked and expanded. After an introductory chapter and the chapter "Schritt fuer Schritt durch den SUP-Prozess" (step by step through the SUP process), the third chapter is "SUP in Osterreich" (SUP in Austria). This chapter contains documentation of strategic environmental assessments that have been conducted in Austria, in which 250 such assessments are categorized according to planning sectors, and a number are described in detail. This chapter also describes the seven Austrian SUP pilot projects and the SUP activities of the federal and regional governments. The next chapter, "SUP international," describes examples in other countries, and provides information about environmental assessment in the EU and in particular EU countries, in the USA and other non-European countries, as well as developments in environmental assessment at the international level. Chapter 5 presents the legal basis of environmental assessment. This includes international laws concerning environmental assessment, the environmental assessment guidelines of the EU, the environmental assessment protocol of the UNECE, as well as all relevant Austrian laws and ordinances. The concluding chapter provides an environmental assessment checklist as well as a list of related literature and web-links.