This special issue of the Netherlands' Journal of Social Sciences brings together various perspectives on solidarity, each highlighting different aspects and dimensions of this highly complex concept. The following conclusions can be drawn on the basis of the articles in this issue. In the first place, a solidarity-oriented personality type seems to exist. Personality traits appear to be stronger determinants of solidarity than socio-economic factors. Secondly, differences in cultural capital may explain the fact that group members exhibit solidarity in one respect, but not in other respects. Thirdly, different types of social ties are involved in social interaction, leading to differences in the way solidarity is experienced and expressed. A fourth conclusion is that solidarity is determined by the level of interdependency between actors as well as by the social context in which actors cooperate. Fifth, institutional characteristics of the polity, in particular the specific character of its political and administrative structures, have an impact on the way solidarity is experienced and becomes organized. Solidarity, then, is manifested at different levels, from the individual and group levels to an institutional level, and it is affected by psychological as well as socio-cultural and contextual factors.