This guidebook, developed by the Technical Support Working Group (TSWG), and Department of Homeland Security (DHS), provides information for enhancing the security of Supervisory Control and Data Acquisition Systems (SCADA) and Industrial Control Systems (ICS). The information is a comprehensive overview of industrial control system security, including administrative controls, architecture design, and security technology. This guide is intended for all sectors that use SCADA or ICS technology. This is a guide for enhancing security, not a how-to manual for building an ICS, and its purpose is to teach ICS managers, administrators, operators, engineers, and other ICS staff what security concerns they should be taking into account. Download the public release limited version here, or request the full publication on line from the Government Printing Office http://bookstore.gpo.gov. The GPO Stock Number is 008-022-00338-0, and the price is $17.