Strategic Environmental Assessment (SEA) has been recognised as an useful aid in integrating environmental considerations into strategic planning to improve the environmental performance of policies, plans and programmes making. Despite of the application of its principles around the world, it is appreciated that there cannot be one SEA model that can fit all planning processes and systems. Each planning system, with its own legal, administrative and procedural frameworks, has to establish its own SEA system that takes into account national and local policies, government machinery, planning legislation. This paper seeks to provide an assessment review of SEA application in 10 selected countries worldwide. Five countries were selected from developed counties which are considered as pioneers in environmental assessment. The other countries were developing countries, with relatively similar contexts to the country of case study, which recently have an increasing attention to environmental issues. These have been selected to present countries where SEAs have been routinely applied for some considerable time, in order to gain some understanding of how SEA is applied in different contexts. This assists in exploring differences in SEA practices in different systems in order to capitalise on international experience due to limited resources covering this. This is feasibly important for countries, in particular, developing countries in setting up or update their SEA systems.