From the return to democracy to the present, illegal strikes have acquired a proudnent role in Chile's labor conflicts, mainly due to the fact that many more workers mobilize, compared to those who participate in legal strikes. Nevertheless, existing studies on the subject focus on descriptions and general tendencies, thus neglecting the in-depth analysis of the factors determining the specific occurrence of the extralegal strikes. Consequently, the factors that might be contributing to the possibility of illegal strikes remain unknown. If labor strikes are construed as analytical events that are fundamental in order to understand power relations in capitalist enterprises, the review of the international literature on the subject helps us solve that problem, since it proposes statistical analysis models to study the economy at the national level (economic cycles), trade union organization (membership and size of unions), and work regime (fragmentation and job insecurity), as well as a further company-level analysis of the last two models. On the basis of statistics regarding the strikes that took place in Chile between 1990 and 2015 and a binary logistic regression analysis, we analyzed the weight of each one of those statistical models separately and that of all of them taken together, in the private sector of the economy (in which it is possible to opt for one or the other strike modality in the Chilean case. The results show that the trade union organization and the work regime models have a greater power to determine illegal strikes, and that the economic model loses meaning when its variables are included in the complete model. Filially, the article preset its the conclusions regarding the relevance of the distinction between legal and illegal strikes for the Chilean case, in terms of workers that not only represent subjects without rights, but also actors with a certain autonomy regarding legality. in this sense, these mobilizations lead to the study of the organizational power certain workers have shown in the face of adverse external conditions (both in the law and in the new forms of work), in the context of the tactical debate over how to revitalize Chilean unionism.