Using different measures of self-reported and other-reported environmental behaviour (EB), two important theoretical models explaining EB--Hines, Hungerford and Tomera's model of responsible environmental behaviour (REB) and Ajzen's theory of planned behaviour (TPB)--were compared regarding the fit between model and data, predictive ability, solidarity of the model structure and model modifications. Results of structural equation modelling revealed that the predictors in the TPB model explained much more variance in behavioural intention than those in the REB model (approximately 69 vs. 37%) but the two models differed little in explaining the variance in EB (about 75% with self-reported measure and 26% with other-reported measure). In addition, both suffered weakness of ineffective paths in the model structure. It was found that the operationalizations of the variables in the models might affect the results of the tests of these models and some adjustments and examinations were suggested. Although the REB model was shown to be imperfect in many aspects, it should be evaluated from a different viewpoint and was encouraged to be applied and tested in the context of environmental education. (Contains 3 figures and 5 tables.)