The number of initiatives aimed at the evaluation of Sustainable Forest Management has risen considerably since the UNCED Conference in Rio de Janeiro in 1992. In a large number of countries and regions standards with Principles, Criteria and Indicators of Sustainable Forest Management (SFM) have been developed. In many cases, this development took place within the framework of an intergovernmental or international initiative. Sometimes the initiative was taken by national or local organisations. Standards were often developed for the purpose of forest certification. In this research, 164 standards for SFM were collected worldwide and compared using multivariate statistics. The comparison was carried out using a reference standard specially designed for this purpose. It is a generic tool that can be used for any comparative study between the contents of standards. Although a number of typical sustainability elements are present in most standards, differences between standards are substantial. The main cause of variation between standards is the difference between levels of application. Standards developed for the National level are less detailed and contain many elements concerning monitoring aspects to be evaluated at sub-national scale. The more detailed standards for assessment at the Forest Management Unit (FMU) level combine monitoring aspects with a large number of management aspects. These different conditions between FMU and National/Sub-National Level and, therefore, the need for level-specific Criteria and Indicators are well known and accepted by the forestry profession.

A second and less known cause of variation between standards is the difference in geographical origin. The observed geographical differences between standards can be explained by biophysical and socio-economic differences between countries and regions. Standards from developing countries in the South most often emphasise the social and economic aspects of sustainability, while they give little attention to the need for research-based information. Standards from industrialised countries in the North on the other hand, strongly emphasise the ecological forest functions and the need for research-based information. Harmonisation among standards is only recommended as far as differences are caused by a lack of capacity or by socio-economic inequity. These deficiencies should be eliminated through international cooperation in order to obtain a more harmonised standard of SFM throughout the world.