Under the current conditions of unstable economic, social and environmental development, the organizations’ need to develop responsible business practices based on the principles of sustainable development is increasing. For a timely response to the modern challenges, organizations need established and clear global schemes adding to set sustainable development principles into organizational activities. The purpose of this study is to interpret the concept of «sustainable development of the «organization and explore different approaches to its assessment (both in foreign and Russian practice). In this regard, the article reveals the definition of «sustainable development of the organization» in terms of a balance of economic, environmental and social components and meeting the needs of stakeholders in the long term; we have considered the leading practices in assessing the level of sustainable organizational development and identified their common features. Based on the experience of leading organizations, we modeled our own method of assessing the level of sustainable development based on system of indicators, which is meant for analysis of the enterprise’s key areas. This methodology involves calculating a composite indicator of sustainability relying on the estimated particular integrated indicators (sustainability of external environment, financial-economic, social and environmental sustainability), which will allow to assess not only the quantitative but also the qualitative indicators.