Trade in intermediate inputs now accounts for as much as two-thirds of international trade. Firms must decide which segments of their production processes to own and which to outsource. Using global plant-level data, this column empirically examines firms’ organisational choices along value chains. Decisions to integrate or outsource upstream and downstream functions are found to depend on demand elasticity relative to the substitutability of inputs. These results provide strong evidence that integration decisions are driven by contractual frictions.