Much user generated content (UGC) is produced or reproduced by volunteers. Many UGC platforms exist nowadays to facilitate the process of co-production. The majority of them, however, show a gender imbalance of their contributors’ communities, including platforms for collecting Volunteered Geographic Information (VGI). Causes of this gender imbalance have not yet been elaborated sufficiently. In order to identify some of these factors which influence women’s participation in UGC platforms, case studies were carried out to compare different spatially explicit, spatially implicit, and non-spatial UGC projects. The case study analysis is based on a conceptual framework used to analyse participants’ motivations for contributing VGI in reference to gender. The findings suggest several criteria related to the imbalance of female and male contributors in the field of VGI.