Civil society activism in traditional non-governmental organizations (NGOs) is seen as one of the cornerstones of a vibrant participatory liberal democracy in most Western democratic states. Whereas this issue has been explored from a variety of perspectives in a Western context, only limited research has been carried out in a post-Soviet context. This study presents unique survey data on civil society core activism in post-Soviet Latvia addressing the following two main questions: What are the characteristics and factors that influence a person to become a core activist in a civil society organization? How does the post-Soviet Latvian context influence civil society core activism? Two nationwide surveys were carried out among core activists in all sorts of NGOs and for a comparative purpose among the population at large, from which non-activists have been extracted. Through cross-tabulations based on the three comparative dimensions: a) activists in general vs. non-activists, b) fields of interest and c) position in organization, this study indicates that many of the factors proven to be important when explaining civil society core activism in Western contexts also have explanatory power in post-Soviet Latvia. Important factors are an individual’s educational level, empathic ability and level of civic literacy, as well as the presence of activist role models and positive support for the decision to become involved in civil society activism. Citizenship and gender are other important factors, but unlike Western countries women dominate the civil society sector in Latvia. Two new factors are also suggested and tested, showing that the perception that one has the ability to organize activity and prior leadership experience from a communist organization are important for Latvian core activists. Binary logistic regression analysis is further used to test the significance of each of the independent variables alone and in combination with each other, introducing different types of core activists based on gender, motives for activism, intensity of political, charity and recreational activity, as well as the positions they have in their organizations.