This study investigated environmental attitude as a mediator in the relationship between self-concept,
environmental-self-efficacy and responsible environmental behaviour among residents of high-density areas in
Ibadan metropolis. The sample consists of one thousand, three hundred and sixty participants that comprised
five hundred and seventy six from Ibadan South East and seven hundred and eighty-four from Ibadan North East
Local Government areas selected using a multi-stage sampling technique (purposive, proportional, and simple
random). Data collection was through a self-reported questionnaire that measured demographic factors, selfconcept,
environmental-self-efficacy, environmental attitude and responsible environmental behaviour.
Multiple regression statistical analysis is the technique of data analysis. Results indicate that self-concept,
environmental self-efficacy, and environmental attitude jointly contribute 18% to variance in responsible
environmental behaviour. Independently, self-concept (ß?? -0.16., t ? -4.82., p < .01) and environmental-selfefficacy
(ß ??? -0.11., t ? 3.08., p < .01) respectively contributed significantly to responsible environmental
behaviour. Lastly, environmental attitude (ß ??? -0.23., t ? -8.53., p < .01) significantly mediates the relationship
between self-concept, environmental self-efficacy, and responsible environmental behaviour. Discussion focuses
on the relevance of environmental attitude in the person-environment transactions. It was recommended that
psychologists should design personally relevant environmental attitude change strategies to improve
responsible environmental behaviour