According to a first aspect of the present invention there is provided a method of implementing policy management in an IP Multimedia Subsystem, IMS, for users that are part of an organisation or enterprise. The method comprises the steps of separating the users into a plurality of groups, each group being defined by a Group Document that is managed by an XML Document Management Server; for one or more of the groups, including one or more policies in the Group Document of the group; for each of the groups, including in the Group Document identities of groups to which the group is related; and when determining one or more policies that are to be applied to a user, taking account of any policies included in the Group Document of the user's group and any policies included in the Group Document of any related groups.