Chapter 4 provides for a comparative review and evaluation of 11 established SEA systems from ten countries worldwide, based on SEA context, procedural and wider methodological factors, as introduced in Chapters 1 and 2. These include systems in five EU and five nonEU countries. An important aim of the chapter is to help those looking for experiences from elsewhere to find systems that may be similar to their own. SEA is likely to be fully effective only in the long term, particularly through changing established routines and attitudes of those involved in PPP making (see Chapter 1). Therefore, only systems are considered where SEA has been applied routinely for some considerable time, normally for at least over a decade. Regarding EU examples, only member states are considered that had pre-Directive SEA practice in place.