This paper establishes environmental attitude as a powerful predictor of ec
ological behaviour. Past studies have failed in this enterprise because the
y did not consider three shortcomings that limit the predictive power of en
vironmental attitude concepts: (1) the lack of a unified concept of attitud
e, (2) the lack of measurement correspondence between attitude and behaviou
r on a general level, and (3) the lack of consideration of behaviour constr
aints beyond people's control. Based on Ajzen's theory of planned behaviour
, the present study uses a unified concept of attitude and a probabilistic
measurement approach to overcome these shortcomings. Questionnaire data fro
m members of two ideologically different Swiss transportation associations
are used. This study confirmed three measures as orthogonal dimensions by m
eans of factor analysis: (1) environmental knowledge, (2) environmental val
ues, and (3) ecological behaviour intention. One other measure, general eco
logical behaviour, is established as a Rasch-scale that assesses behaviour
by considering the tendency to behave ecologically and the difficulties in
carrying out the behaviours, which depend on influences beyond people's act
ual behaviour control. A structural equation model was used to confirm the
proposed model: environmental knowledge and environmental values explained
40 per cent of the variance of ecological behaviour intension which, in tur
n, predicted 75 per cent of the variance of general ecological behaviour. (
C) 1999 Academic Press.