This article reassesses the history of reparations after World War I from the perspective of organized labour in early Weimar Germany. It does so by investigating trade union proposals to send German construction workers to Northern France in an effort to rebuild French villages damaged or destroyed in the war. The article argues that organized workers in early Weimar Germany rallied behind these proposals not only because they hoped that sending fellow workers abroad would contribute to international reconciliation, ease the overall reparations burden, and create employment opportunities, as previous research has suggested. Rather, it shows that Weimar’s “free” (that is, socialist) trade union movement supported the idea of “reparation through labour power” because its members were convinced that it would prevent the rebuilding of Northern France from becoming a playground for private builders. Analysing various German trade union sources, the article suggests that, by involving the country’s nascent Bauhütten movement, a network of building companies owned and controlled by organized labour, trade union functionaries hoped to turn Northern France into a laboratory for non-profit construction. In doing so, they sought to advance a broader transformation of the building sector from a profit-seeking industry benefiting a few wealthy builders into a public service that promoted the interests of workers and the wider community alike. By exploring these trade union proposals for the reconstruction of Northern France, the article also sheds light on a neglected episode in transnational labour history that witnessed the first timid attempts at trade union representation across borders.