This paper examines demand for and access to private-sector extension services by contracted cotton producers in northern Tanzania. Data from a non-random survey of 520 smallholders show that only 21.9% received any extension and only 4.6% received extension from the cotton ginnery. Wealthier households were three times more likely to receive extension from any provider. While the public sector remains the main source of extension and is prioritized by smallholders, almost all households demanded extension from firms and are willing to invest 3 days per month mainly for advice on cotton and maize production. The involvement of third parties in the supply of extension from ginneries could not only meet smallholders' demands but could increase cotton supply and repayment rates to the firm, and thus finance the provision of missing extension advice.