The Manchester Chamber of Commerce established the Manchester Testing House in 1895, and introduced uniform yarn contracting rules in 1897. The chamber made these institutional “innovations” to deal with the nefarious practice of “short-reeling.” This case study explains how and why merchants were crucial to undoing weaknesses in domestic —and to some extent foreign—legislation to overcome this fraudulent activity. We argue that the Testing House and uniform contract were tantamount to developing a quasi-legal system such that private standards established through cooperative agreements had legal sanction. Our study shows how institutions evolved to improve governance along the supply chain for this highly specialized export-orientated industry. This article contributes to the growing literature on historical markets, institutions, and standards. Based on extensive archival sources, we show how specific and complementary commercial institutions developed within grounded notions of governance rather than abstracted spaces of market exchange.