Three studies were carried out to examine how place attachment and collective action tendency are related and what role self-expansion and social interactions play in this relationship. In the first study (N = 156) we found that a more active form of attachment – place discovered – is a significant predictor of tendency to engage in collective action in favor of one’s neighborhood. In the second study (N = 197), we focused on frequency of social interactions in one’s neighborhood as the antecedent of place attachment and collective action tendencies. We found that inhabitants who declared more frequent social interactions in one’s neighborhood, expressed stronger place discovered, and this attachment is related to collective action tendencies. In the third study (N = 153), we tested if self-expansion mediates this relationship. We found that stronger place discovered was related to the feeling of self-expansion that resulted from contact with neighbors. Moreover, self-expansion was related to the tendency to engage in collective action.