Solidarity is probably one of the most frequently used terms in recent times, but it is far from being clear what it means. In fact, solidarity does not only appear in many policy areas – the social policy field might be the most prominent one – and is often invoked by political actors, but also the scholarly debate on solidarity increases steadily. Nonetheless, there is no unifying definition of solidarity or an analytical framework that captures solidarity in its complex and multifaceted dimensions. We rather see a plethora of approaches and understandings of solidarity across the social sciences. While this is per se no disadvantage and might illustrate the contextuality of solidarity, a systematic framework would make it possible to identify the central characteristics and help to explain similarities and differences in the state of solidarity.

The background of the present book, edited by Christian Lahusen, is the interdisciplinary research in the Horizon2020 project TransSOL “Transnational Solidarity at Times of Crisis” between 2015 and 2018. The edited volume presents such a systematic framework on (European) solidarity, combines various data sources as well as applies multiple methods across eight different European countries (Denmark, France, Germany, Greece, Italy, Poland, Switzerland and the United Kingdom) and with regard to the issues of unemployment, migration and disability. The edited volume links the overall framework of the project to the different areas that were analysed. The introduction provides an encompassing definition of solidarity that is based on three central aspects: Solidarity is a disposition (1) or practice (2) that relates to other social groups (3) and is based on expected mutual support (4) for each other. Additionally, the project distinguishes between the individual level (micro), the organisational level of civil society actors (meso) and the political-state level (macro). By doing so, the edited volume contributes to the various fields in the study of solidarity: social policy and welfare state research, (European) political sociology and social movements studies as well as communication and media science.

The chapters two to seven analyse the various data sources (survey, organisational data, legal texts, print media and social media) regarding the state of European solidarity and try to explain differences and commonalities that are under research. The last chapter summarises the results and discusses the implications of the findings. Instead of summarising the main results of each chapter separately, I want to highlight four results that appear in various chapters. Firstly, and most importantly, solidarity is highly contested in Europe. Even though inscribed in legal texts (ch. 5), institutionalised in the welfare sector (ch. 4) and an important frame to mobilize and persuade others in the public sphere (ch. 6 and 7), the edited volume sheds fresh light on the question who acts in solidarity with whom under which circumstances.

Secondly, and in line with previous studies on the subject (Gerhards et al., Reference Gerhards, Lengfeld, Ignácz, Kley and Priem2020), the authors show a relatively high level of European solidarity across countries. Despite the multiple crises that European countries have experienced – though to various degrees -, the European level is an important reference point for people to show mutual support, create a sense of belonging to others and as an opportunity to share resources and to minimize risks (ch. 2). It demonstrates that the public appeal to European solidarity resonates in the public (ch. 6) and among the population (ch. 7) in their communicative exchanges. Otherwise, the findings of the conducted survey also demonstrate a gap between national solidarity and European solidarity (ch. 2). While the majority of respondents supports reducing inequality in their own country and also supports the idea of humanitarian aid to foreign countries, these dispositions do not automatically translate into the support of institutionalised solidarity at the European level. A similar gap is shown with regard to reported solidarity attitudes and reported solidarity actions on the national and European level.

Thirdly, the various contributions show how transnational solidarity is embedded in national and local contexts. Especially in the case of civil society organisations (ch. 3), their actions predominantly take place at the local level, emphasizing the direct mutual support that these organisations provide for people in need. This highlights an important aspect in the study of solidarity, because it disentangles the scopes of solidarity and the scopes of the respective actors. Moreover, the cross-national differences highlight that European solidarity is perceived differently and is shaped by socio-cultural and political-institutional factors.

Fourthly, moments of crisis and crisis experiences are important drivers for solidary attitudes and actions. The establishment of civil society groups, NGOs and any other related transnational solidarity organisation coincides with moments of crises (ch. 3). People are mobilised in hard times and talk about it in their online comments (ch. 7). In particular, the European migration crisis 2015/16 underlines that crises, perceptions and acts of solidarity are interlinked and create a shared issue that is of interest for political actors and ordinary citizens (ch. 6 and 7) (Wallaschek et al., Reference Wallaschek, Starke and Brüning2020).

Accordingly, the central claim of the book that solidarity is highly contested seems to be a matter of belonging and social boundary-making, limited resources as well as institutional factors that shape solidarity actions and attitudes. Moreover, the edited volume highlights that the often proclaimed necessary decision of either national or European solidarity does not hold true, while in fact, expressing and practising solidarity or not seems to be the bigger divide in Europe. Consequently, it underlines that there is a tension between on the one hand the multiple claims in public speeches, in legal treaties and by civil society groups and on the other hand weakly and uneven implemented European solidarity, limited and conditional solidarity attitudes and practices towards certain social groups as well as contentious debates on solidarity in the European migration crisis 2015/16. The edited volume presents a multifaceted mosaic artwork of European solidarity that enriches the conceptual and empirical debates on solidarity and will have a great impact on future studies in this subject area.