The NEP (New Ecological Paradigm) scale is an internationally used measure of environmental attitudes and a predictor of pro-ecological behaviours (Dunlap, Van Liere, Merting, & Jones, 2000). In the current study we investigate the factor structure of the scale in order to state if it fits the theoretical model concerning the Polish population. We use the GEB (General Ecological Behaviour) scale as a test of the convergent validity of NEP scale results. The online study made use of a convenience sample of people aged 17–68 years, N = 305. Our study revealed that the theoretical concept of the NEP scale, including its five-factorial solution proposed by the authors of the scale, does not fit our results. After having conducted the exploratory structural equation modelling (ESEM) we found a two-factorial structure to be more appropriate, but the newly revealed solution was still not completely satisfactory according to the obtained psychometric parameters. Convergent validity of NEP was confirmed. However, socio-demographic characteristics of participants in the study were not related to the frequency of pro-ecological behaviours in general.