The authors proposed a method for evaluating the level of cooperation among associations for sustainable development and their participants. The indicators of the structure, of the scale and the diversification of cooperation have been selected by expert method. As a result, the method classifies participants, including entrepreneurs, by level of cooperation. Researchers have proposed classes of participants in cooperation for sustainable development. This classification is based on the grouping methods and calculation of the interval. If the participant had higher class, this means the participant had the closer links in the cooperation for sustainable development, and vice versa. This assessment allows us to determine the desire for cooperation of each participant (entrepreneur, NGO, investor, university, government). The method has been tested on the basis of 12 associations for sustainable development, including 951 participants for 2021. Between 1964 and 2020, the importance of large entrepreneurs increased in associations for sustainable development, especially the chemical entrepreneurs. The growth rate and the share of other participants are insignificant compared to large entrepreneurs in the associations. Small and medium-sized entrepreneurs have barriers to entry into associations. It is necessary to form a partnership of all participants for the sustainable development at the same time.