I have to populate my autocomplete PeopleEditor-like control based on brililant [ASPTokenInput][1] with all people from my AD domain. Reflecting PeopleEditor shows a real mess in their Active Directory search engine and all potentially helpful classes are internal. My test method works fine, but I need to get ALL users from AD(not sharepoint site ones) to populate my list: ![How it looks][2] public string GetUsers(string filter) { var spWeb = SPContext.Current.Web; SPUserCollection allusers = spWeb.AllUsers; List<SPUser> users = allusers.Cast<SPUser>().ToList(); var query = from spUser in users.Select(usr => new {id = usr.ID, name = usr.Name}) .Where(p => p.name.IndexOf(filter, StringComparison.InvariantCultureIgnoreCase) >= 0) select new {id = spUser.id.ToString(), spUser.name}; return new JavaScriptSerializer().Serialize(query); } How can I query active directory like this? Is it possible to retrieve all AD connection settings from sharepoint itself? I need just id and user name to fill my dropdownlist Converting this to SPUserCollection is another big deal. It would be great to use some built-in SP methods like this: [SubsetCallableExcludeMember(SubsetCallableExcludeMemberType.UnsupportedSPType)] public static SPPrincipalInfo ResolveWindowsPrincipal(SPWebApplication webApp, string input, SPPrincipalType scopes, bool inputIsEmailOnly) { return ResolveWindowsPrincipal(null, webApp, input, scopes, inputIsEmailOnly); } [1]: https://github.com/harindaka/ASPTokenInput [2]: https://i.sstatic.net/Tcz8m.png