This paper looks at market access and national treatment commitments for services in the General Agreement on Trade in Services (GATS) and in 95 regional trade agreements (RTAs) involving the countries that are covered in the OECD Services Trade Restrictiveness Index (STRI). The objective is to quantify the impact of legal bindings on trade in services that result from a reduction in the uncertainty faced by exporters. Bilateral bindings indices are created for five broad service sectors (professional services, computer services, telecoms, financial services and transport services). They indicate how close the sector is from a fully bound regime with no possibility to introduce any new trade barrier, by comparing commitments with the actual trade regime. These bilateral indices are then tested over the period 2000-2014 in a structural gravity model. Despite differences across sectors, the results confirm that the legal bindings typically found in services trade agreements tend to have a positive impact on exports even if no actual liberalisation takes place.