Having overcome the prejudice that equated emotion with irrationality, collective action theories are beginning to incorporate emotional variables. Nonetheless, these are restricted to negative ones, fundamentally anger. This is due to the fact that collective action is associated exclusively with protest, when this does not necessarily have to be the case. The aims of the present work are twofold: a) to analyse the structure of emotions with regard to the Spanish Government's decision to negotiate with ETA; and b) to verify the impact of these emotions and of ideology on the intention to participate in demonstrations supporting or protesting against said decision. The results show that emotions can be organised into three factors: anger, enthusiasm and anxiety. Anger and enthusiasm account for a high percentage of variance in the attention to demonstrate. Ideology, although to a lesser extent, also has a significant influence