ENThis study aims to provide an empirically verified exploration of factors influencing environmental activist behaviour. The authors focus on the determinants of personal environmental activist behaviour as a characteristic of the culturally specific group of Central and Eastern European (CEE) countries. A two-stage model of the biographical availability thesis is explored. Results reveal evident regional differences in patterns of public-sphere environmental behaviours across Europe. CEE countries exhibit lower levels of engagement in environmental activist behaviours than Western and Nordic European countries. The two-stage model of the biographical availability thesis is only partially confirmed. Age and employment status have a significant influence on behaviour: specifically, being 17–24 years old and in education increases availability for environmental activist behaviour. Gender has an additional influence upon participation in demonstrations and protests, with men being more participative. A low-commitment partnership status has additional influence on behavioural intentions. The results imply the need for further research into the context and cognitive determinants of environmental activist behaviour in CEE countries.