The comprehensive and systematic study of collective action organizations (AOs) requires a new methodological approach that takes into account the rise of online sources as well as the new ways in which people interact and participate in politics. This paper aims to present and situate in the related literature such an approach, which was recently created and applied in two European Commission funded research projects, across nine and eight countries respectively. Moving beyond recent studies using online sources, our research uses a hubs-website based approach to study alternative AOs in the LIVEWHAT project as well as transnational solidarity AOs in the TransSOL project. The hubs and subhubs websites which aggregate data on AOs in multiple regions are scraped in order to identify national samples that offer an advanced coverage of the repertoire of AO activities, as defined by the teams. These nodal-websites, which categorize alternative activities of AOs according to multiple repertoires of action and location, comprise the resources from which the population of AOs is composed and from which a random sample is drawn for coding purposes. Thus, hub websites are used as sources, similarly to the way in which newspapers are treated in protest event analysis. The paper situates and compares the new Action Organization Analysis (AOA) approach to its foundational protest event, protest case and political claims analysis, as well as other approaches offering data on online activism. It outlines its main features and the related data construction process, while it showcases its application in two EC cross-national projects. Finally, its merits and limitations are discussed, including how it can be used as a foundation of a mixed-methods approach to study AOs by combining three types of data.