MSDN Library (Platform SDK, ADSI, and other technical programming information):
Active Directory Service Interfaces Overview (links to resources and downloads):
It is advisable to download the updated version from the Microsoft Platform SDK page. You can only select and download the necessary files:
Microsoft Active Directory Services Interfaces 2.5 and SDK (or Active Directory SDK; code and documentation):
MSDN Online Windows Development Center:
Online documentation — click Networking and Directory Services | Active Directory, ADSI, and Directory Services | SDK Documentation | Directory Services.
System Administration Scripting Guide Series ("Disclaimer: The article(s) for this guide series is derived from the System Administration Scripting Guide, a new book that will ship as part of the Windows .NET Server Resource Kit"):
Windows Scripting Solutions (a new resource for administrators):