Environmental issues are an increasingly salient aspect of party competition and voters’ political preferences. Yet political behaviour research often considers environmental attitudes as a component of a broader ‘second-dimension’ and either subsumes it into this or omits it. Using data from the 5th wave of the European Values Study, we demonstrate through factor analyses that environmentalism loads as a separate dimension across Western Europe, that environmentalism has somewhat different social predictors, and that it has important effects on party preference that differ from those of other second dimension issues. Our findings have crucial implications. Firstly, ignoring environmentalism in studies of political behaviour misses an important part of the picture. Secondly, subsuming environmentalism into a broader “cultural” dimension may lead to incomplete conclusions about both social predictors and the electoral consequences of political attitudes and values. Thus, allowing for a separate environmental dimension opens up novel perspectives on political representation in Western democracies.