In two studies we analyzed the predictors of participation in an Italian Lulu mobilization, rooted in the Susa Valley, a North-Western Italian valley where a high speed railway (HSR) should be sited. Based on the data of qualitative Study 1, performed interviewing 12 anti-HSR militants and 12 non anti-HSR militants, we hypothesized that Klandermans' (1997) model on participation (centered on group identification, sense of injustice, and collective efficacy) is suitable to predict the Lulu mobilization we studied, and that three contextual variables (community involvement, the perception of the existence of a vast majority in the community favoring the mobilization, and place attachment) may be added to Klandermans' to predict such a mobilization. We formally tested such hypotheses in quantitative Study 2 (representative sample of the people living in the Susa Valley, N = 250). Results supported the role of Klandermans' (1997) variables and confirmed the influence exerted by our contextual variables, thus suggesting that an integration of the two models would be fruitful in the analysis of Lulu mobilizations. Limits and future developments of this research are discussed.