The basement membrane is essential for epithelial tissue organisation and function but what restricts the basement membrane to the basal periphery of epithelial tissues and what are the basement membrane-mediated signals that regulate coordinated tissue organisation? On p. 411, Melinda Larsen and colleagues use cultures of embryonic mouse submandibular salivary glands to investigate these questions. They show that inhibition of the Rho kinase ROCK in these cultures results in basement membrane accumulation throughout the epithelial compartment. ROCK-mediated control of Par-1b localisation in the outer basal epithelial cell layer (which produces basement membrane) is responsible for normal basal basement membrane positioning, they report. Moreover, inhibition of Par-1b kinase activity prevents basement membrane deposition and disrupts tissue organisation. Conversely, overexpression of Par-1b drives ectopic basement membrane production. These and other results suggest that Par-1b is a master regulator of basement membrane deposition in developing salivary glands and that ROCK control of Par-1b function is essential for normal epithelial integrity and organisation.