Resource based theories propose that firms grow by diversifying into products which use common capabilities. We provide evidence for common input capabilities using a policy that removed entry barriers in input markets to show that the similarity of a firm’s and industry’s input mix determine firm production choices. We model industry choice and economies of scope from input capabilities. Estimating the model for Indian manufacturing, input complementarities make firms 5% more likely to produce in an industry and are quantitatively as important as time-invariant drivers of co-production rates. Upstream entry barriers were equivalent to a 9.5% tariff on inputs.