The theory of planned behaviour (TPB), proposed by Icek Ajzen in 1985, was applied to the study of the implementation of the 'Keep Zambia Clean and Healthy" campaign, a behaviour change programme aimed at keeping surroundings in Zambia clean, healthy and green in order to improve health standards of Zambians throughout the country. The determinants of pro-environmental behaviour postulated by the theory were studied in the light of the implementation of the programme. The survey randomly selected and interviewed 545 respondents, who were heads of household, in Lusaka and Mumbwa, using a closed-ended questionnaire. Following Schwartz (1992), respondents rated their responses on a 4-point or 5-point scale. Consistent with earlier research, the study found a gap between the knowledge and values held by the respondents on one hand and their behavioural action on the other. While the respondents professed good knowledge about the benefits of living in clean and sanitary environments, their behaviours did not show that they had engaged in environmentally friendly behaviour. The results, therefore, showed that giving people information alone may be too limited to bring about desired environmental behaviour.