This paper presents a new and innovative approach to assessing Vocational Education and Training (VET) organizations institutional sustainability in terms of five key pillars: institutional capacity, environmental, economic, social, and training provision. In the five areas of the proposed new and original sustainability assessment framework, a total of 40 performance indicators are used to make the assessment. The assessment process is based on a novel approach for the couple values for performance and importance of the indicators, by using scales from 1 to 5 for both. There are five performance categories (awareness, measures, action, innovation and excellence) and five importance categories for each indicator. The framework is innovative, both by its objective, which consists in impact determining and improvement on environmental, economic, social and quality of the training system and by development of a strategy based on performance indicators that integrates sustainable development. The implementation methodology is based on the newly developed framework and detailed application guidelines are provided. Exact results from a case study carried out and an analysis of the results for the environmental area are presented in order to validate the methodology in action. The results are used to establish a sustainability baseline, to identify possibilities for improvement, and to prioritize implementation.