Many economies have seen growth in industrial clusters during their industrialization, and the relational contracts between manufacturers and subcontractors are often the organizational basis of clusters. We predict that, if manufacturers form relational contracts with subcontractors, if manufacturers closely collude with each other when trading with subcontractors, if information about subcontractors’ past actions is only imperfectly shared by manufacturers as hearsay, and if demand shock is considerable, then premium subcontractors suffer more from market volatility than ordinary subcontractors would and hence, it is optimal for manufacturers to shield premium subcontractors against the risk. We then study Kiryu, a kimono weaving cluster that expanded from the late nineteenth century with the development of new synthetic dyeing techniques. We show that premium subcontracting weavers were allowed long‐term relational contracts and specialization, which shielded already honest weavers against market volatility and induced them to be diligent and to acquire skills.