Two key concepts, irregularity and solidarity, are examined based on the preliminary findings of the Immigrant Work Strategies and Networks project at COMPAS. Irregularity can refer to immigration status or to the position of immigrants within the labour market. A significant finding of the project is the flexibility or fluidity with which immigrants move between regularity and irregularity. The various ways in which solidarity allows immigrants to accommodate irregularity are illustrated through a discussion of how collective social relations operate for Turkish immigrants in the process of developing work strategies in London. Collective social relations within the compatriot community enable immigrants to accommodate various kinds of irregular status, yet the outcomes are positive for some while exploitative for others. The state can also undermine solidarity through policies and regulations. Ultimately, the development of viable work strategies includes a process of accommodation and resistance to global and local labour market conditions, to the enabling and restricting state, and to the constructive and exploitative nature of social networks. In this paper, we introduce a more differentiated analysis of solidarity and of immigrant and labour market statuses. We introduce a notion of irregular formality to help us understand this complex social process.