With coalition talks that could last months under way to form Germany’s next government, the reverberations of Sunday’s election will be felt for quite a while. But one of the most significant developments in voters’ weekend trip to the polls was a local referendum in Berlin, which strongly endorsed a campaign to expropriate properties owned by large corporate landlords. More than a million Berliners supported the campaign Expropriate Deutsche Wohnen & Co, which targeted companies holding 3,000 or more apartments (Deutsche Wohnen is one of the largest investment trusts in the city). In total, 240,000 properties, or 11% of all apartments in Berlin, would come under the terms of the initiative, which was backed by a majority of 56.4% in the referendum. The vote isn’t legally binding, however, so it is now up to the city’s government, which was also elected on 26 September, to decide whether to move forward. And while struggles over housing are nothing new in Berlin, this successful campaign marks a potentially transformative moment – one that could have a major impact on housing struggles in other cities, and also serve as a template and inspiration for activists in Europe and elsewhere. The campaign to resocialise housing in Berlin (Vergesellschaftung) was launched in 2018, in response to the rapid financialisation of housing in a city where €42bn was spent in large-scale real estate investment between 2007 and 2020, more than London and Paris combined. Smaller landlords and state-owned social housing have been aggressively targeted by large institutional players for whom housing has become a vehicle for the management of global capital funds. For ordinary tenants in Berlin, where at least 80% of the population are renters, the transformation of the housing market was accompanied by skyrocketing rents, widespread displacement and the dismantling of local communities and social bonds. Many neighbourhoods were rapidly gentrified while low-income residents struggled to find decent affordable housing. The real ingenuity of the expropriation referendum campaign was its use of the German basic law to make its case, as set out in the 1949 German constitution, which states that “property entails obligations” and “its use shall also serve the public good”. The constitution allows for the socialisation of private assets “by a law that determines the nature and extent of compensation”. Many legal experts also agreed that taking back housing into social ownership was permissible under the constitution. Not only did the campaign initially secure the required signatures to trigger a referendum, it submitted more than 350,000 signatures, all while negotiating the many challenges of the pandemic. This was testament to a remarkable grassroots effort rooted in local neighbourhood teams spread across the city’s districts. Working groups were also established that focused on key legal and financial issues and, in recent weeks, the vote itself. After its victory, the campaign has been quick to call upon the next Berlin senate to recognise the result, and draft a new law on putting housing back into social ownership. As with the federal government, the shape of the new governing coalition in Berlin itself is not yet clear, though local politicians – with the exception of the leftwing Die Linke party – have expressed little appetite for housing resocialisation. The city’s prospective mayor, Franziska Giffey of the centre-left SPD, has already strongly ruled out the idea, but the scale of the referendum victory will be hard to ignore and she has indicated that she will respect the result. The campaign has already drawn up a legislative proposal in an attempt to put further pressure on the Berlin senate. Efforts to enact the socialisation process will undoubtedly face legal challenges, not to mention the problem of compensation of the property corporations. Campaigners are adamant that their model would balance a commitment to fair compensation with “budget-neutral” socialisation. Some commentators worry that the city will be forced to buy back properties at current market rates and that a major programme of social housing construction may actually be more cost-effective. Whatever the case, campaigners are acutely aware that what they have achieved so far must be part of a wider project to revive “socially oriented” housing construction, including support for a range of non-profit property policies. The referendum represents a potential watershed moment beyond Berlin too. It highlights the role that ordinary tenants – and grassroots organising – can play in developing policies for affordable housing while supporting communities increasingly at risk of displacement. It can be a catalyst for municipal housing movements across Europe. Sunday’s results also offer a potent reminder of the absence of meaningful housing alternatives in the UK despite the tireless (and underappreciated) efforts of grassroots organisations across the country. Berlin has shown how community organising and a committed group of city residents can design and implement a long-term campaign around housing at a scale currently unthinkable in the UK. As David Madden and Peter Marcuse remind us, the contemporary housing crisis – whether in Berlin or here in the UK – cannot be solved by minor policy fixes. What is needed are creative, large-scale solutions that tackle housing insecurity and empower residents to challenge their increasing marginalisation and vulnerability. While some may bristle at the nature (and perhaps radicalism) of the socialisation campaign in Berlin, it has also shown us the power of of tenant activism and community organising. As the Expropriate Deutsche Wohnen & Co campaigners proudly proclaimed: “This is our city, this is our home.” Alexander Vasudevan is an associate professor in human geography at the University of Oxford