Controlled access is provided to a shared resource 23 such as an ontology (knowledge database) in order to maintain its quality without restraining the ability of users 21a, 21b, 21c . . . to contribute to that resource.An edit and query function 26 is used to determine the validity and consistency of individual contributions. The results of these checks and the level of contribution made by individual users to the information resource is used to produce a rating for each user of the resource, which is stored (24a, 24b . . . ) for use in prioritise and manage future contributions to the resource 23, provide metadata on the resource and to prioritise access control 28 to the resource.When a new contribution is made by a user a threshold of approval can be set before it is accepted into the main database 23. This threshold is based on the sum of the ratings points of the original contributor and of users that give their assent to the inclusion of that contribution.