An instrument that political parties use to inform the electorate with regard to their policy preference (including preference towards the environment) is the electoral manifest. This paper analyses some important drivers that push political parties towards adopting pro-environmental attitudes by analysing the content included in their electoral manifestos (using the Comparative Manifesto Dataset). As explanatory factors we consider various socio-economic, ideological and international related variables, but our main focus is on environmental related determinants. We proceed as such because the paper aims to test the validity of ‘the ecological approach’ given that the current literature overlooks this issue or doesn’t succeed in providing strong evidence of its existence. Our dataset covers 49 countries worldwide and a total of 190 national electoral years, occurring between 2000 and 2015. The resulting evidence, which might confirm the validity of ‘the ecological approach’, is rather weak, but there is nonetheless strong evidence to prove the existence of an opportunistic behaviour of the political parties (confirming the validity of the ‘opportunistic political cycle’).