the NAIP project in Bihar are focusing on. Primary surveys were fielded with producers, traders, cold storages, and retailers at the end of 2009 on the rural-urban potato value chain in Bihar, more in particular from the disadvantaged districts part of the NAIP project (Vaishali and Samastipur) to urban consumers in Patna. The most salient findings are presented below.Upstream. First, potato production in Bihar is largely in the hands of smallholders: farmers from the smallest half of potato producers cultivate 0.5 acres of potato. This compares to 1.8 acres for farmers from the largest group. Second, farmers suffer from an important late blight disease problem. Actual potato yields in 2009 were two-thirds lower than the expected yields due to that disease. Despite the incidence of this disease, reported potato yields in the districts are as high as the national level, casting doubts on the national agricultural statistics in vogue which consider Bihar a lagging potato state. Third, farmers rely relatively little on seed markets and almost all farmers store their own seeds in cold storages. Only on 18% of the plots were purchased seeds used, indicating that seed replacement ratios are about 1 out of 5 years. However, larger farmers replace seed more often. Fourth, despite the low use of seed input markets, important changes have happened over time and the white potato variety has now become much more important than the traditional red variety that was usually grown. Especially the larger farmers have switched relatively more to the white variety. Fifth, larger farmers are able to obtain higher yields, possibly because of their more intense use of inputs. Sixth, 70% of the potato farmers are now empowered by a mobile phone. While some farmers use it to do market transactions, this is still only a minority (20%). Seventh, sales in the harvest season are almost all to a village broker while in the off-season, potatoes are mostly sold to traders at the cold storage. Wholesale market sales by the farmers are of less importance. Eight, an important reason why a number, and especially the smaller, farmers sell after harvest is the urgent need of money. Little credit or advances are used in market transactions and the major reason for the choice of a trader is when 2 he pays immediately. Ninth, while almost all farmers participate in cold storages as to store their seeds, larger farmers store relatively much more for sale at an expected higher price in the offseason.Midstream. First, an important boom in cold storage capacity -and thus in potato productionhas happened in the two studied districts. The number of cold storages in the last decade doubled or tripled and rapid up-scaling of cold storages led to an even faster total capacity expansion, i.e. a triple and five-fold increase over the same period. Second, the boom is associated with increasing commercialization of potatoes from the two districts as the share of storage for seed potatoes is relatively on the decline. Third, several triggers explain the boom in thi...