This paper shows that private product standards in EU food and agriculture markets can have significant trade effects. In particular for developing countries and for goods that are perishable or only lightly processed, EU standards can often be trade-inhibiting. However, internationally harmonized EU standards—those that are equivalent to ISO norms—have much weaker trade effects, and in some cases are even trade-promoting. At a policy level, our results highlight the importance of dealing with the trade effects of private standards in major markets, not just mandatory public standards.