The present paper analyses how the design of EU preferences, in particular of their rules of origin, impacts the integration of West Africa into world trade. We show that West Africa?s trade has not yet undergone the structural change typical of countries having successfully established themselves as manufacturing assembly platforms. Complex, restrictive, and discriminatory, EU rules of origin (RoOs) have so far not proved conducive to the integration of African producers in world trade. However, the reform of the EU?s RoOs currently contemplated by the Commission which would consist of replacing the ?single list? of RoOs by a unique instrument could be a step forward in this regard, provided the unique instrument is set at a level of restrictiveness that does not hamper the ability of firms to fragment manufacturing processes and set up complex cross-border value chains.