Current community and ecosystem stability theory is briefly reviewed, including a summary of general correlations between certain environmental parameters and stability, inferred from theoretical and empirical investigations. Two approaches are explored for the application of stability theory to experimental mesocosm studies: (1) use of mathematical models and computer simulations, and (2) use of environmental correlates. An example of the latter type of stability analysis is presented for mesocosm community responses to the herbicide atrazine. Atrazine was found to have a destabilizing effect on the overall mesocosm community, based on its effects on environmental parameters correlated with stability. In addition, a food web complexity measure, l ¯ https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003070016/9f156782-acd7-4662-802e-5f82c033bb45/content/eq106.tif"/> (average number of trophic links per consumer species), was found to be significiantly reduced in atrazine-treated ponds during the second year of a 3-year study. This provided a possible mechanism for the shift from trophic and habitat specialists to generalists. Inclusion of stability analysis in the evaluation of multispecies or ecosystem level toxicity tests is judged as potentially important for giving new insights into how toxins affect the functional mechanics of system integrity. Difficulties in meeting requirements for proper performance and interpretation of stability analyses in typical ecotoxicological mesocosm studies are discussed, with some recommendations for accommodating the requirements in experimental protocol.