Setting out from the relevance of cooperatives worldwide and their important economic and social role, this research aims to understand what motivates cooperators in different segments to be part of a cooperation process with a cooperative. To do so, an exploratory and qualitative study was carried out following the multiple case study method. For data-collection, ten semistructured interviews were held based on a previously defined script. These interviews were recorded and transcribed, followed by content analysis through codification and categorisation. From analysis of the interviews, 37 variables motivating members to participate in a cooperative were identified, with these being grouped according to their similarity in five categories: (1) external influences;(2) characteristics of the cooperative; (3) socio-psychological; (4) relationships; and (5) benefits. Some implications for theory and practice and suggestions for future research are also presented.