1. Agri-environment schemes (AES) have been criticised for being inadequately monitored and for not delivering the expected benefits to nature. Consequently, the Welsh Government funded a comprehensive programme of monitoring of Welsh AES, which took place between 2009 and 2012. The AES assessment focused primarily on Tir Gofal (which translates as “Land in Care”), but also included the Organic Farming Scheme, and monitoring focused on a range of taxa of conservation importance: arable plants, grassland fungi, bats (six species), butterflies (three species), birds (five species), water vole and brown hare. 2. Field work was undertaken to survey these taxa on matched farms and fields within and outside of AES. Response variables consisted of spatial trends of abundance, occurrence and species richness, which were modelled against AES status. Existing data were also available for two bird species. 3. Few differences were observed between AES and non-AES farms and fields. Those that were observed were for species that use arable habitats (which are uncommon in Wales): arable plants, yellowhammers, and brown hares. The lack of differences in non-arable habitats may reflect the smaller contrast between AES and non-AES management in these habitats. It may also reflect the original condition of habitat entered into AES prescriptions, as most non-arable prescriptions were defined by mandatory management of existing habitats, rather than optional habitat creation or restoration, which is the case for most arable prescriptions. 4. Despite the lack of differences observed, AES may help to maintain populations of species, making it more likely that they will persist in the landscape. There is evidence, from this monitoring programme and elsewhere, that AES can increase the populations of species, when well targeted and implemented. 5. Policy applications. The results indicate that Welsh AES have been only partly successful in achieving their stated aim of “maintaining and enhancing species abundance.” These results can be used to improve AES design and management, both in Wales and more widely, by identifying and promoting effective management interventions, and by identifying ineffective management interventions and seeking alternatives. In particular, we highlight the importance of comprehensive monitoring of AES, and we recommend that this be combined with specific targets regarding the expected outcomes of AES management. This is essential to determine whether AES are providing value for money.28-Nov-2018