In many developing countries, pre-shipment inspection (PSI) programs have been implemented to combat corruption within customs administrations. This involves delegating the inspection of imports to private PSI firms operating in the exporting countries. The programs are particularly costly since these firms generally charge between 0.5 % and 0.8 % of the FOB value of the inspected goods. In this article, the authors assess how effective these programs are in the light of contract theory. More specifically, they use the model of hierarchical agency to gain a better understanding of the interactions between the government, the customs administration, the importer, and the PSI company. On the basis of this analysis, the authors then infer various recommendations that involve, among other things, the choice of contractors, the modernization of customs administrations, and recourse to a conciliatory policy.