The European Union Habitats Directive (92/43/EEC) provides for the designation and management of Special Areas of Conservation (SACs) and requires that impacting activities are subject to ¡®an appropriate assessment¡¯ of their implications for the ¡®integrity¡¯ of the site. We define the term ¡®site integrity¡¯ from a legal and an ecological perspective. We demonstrate that ¡®site integrity¡¯ is the maintenance of ecological processes and functions that support the wider delivery of ecosystem services. ¡®Site integrity¡¯ can be influenced by SAC management. Management that seeks to support ¡®site integrity¡¯ may include the use of buffer zones or connecting areas that extend beyond the SAC site¡¯s designated features. We conclude that ¡®site integrity¡¯ and ¡®favourable conservation status¡¯ are powerful legal terms that if fully transposed into the law and policy of Member States can enable the achievement of broader European and International goals for marine conservation.