This series comprises correspondence files focusing on instructions and procedures covering war time operations of the security service and some personal dossiers. It is possible that these files were created by the Security Service (CA 948), which may explain the 'SS' prefix, and were subsequently incorporated into the Investigation Branch (CA 910) and later Commonwealth Investigation Branch 
(CA 914).  The early contents date range is a result of amalgamating papers from ealier Investigation Branch files (specifically SS378).

The records cover a range of subjects including aliens - registration and control, revocation of naturalisation, passports; internees and prisoners of war - transfers, repatriation, employment, detention, reviews, release, conditions and health, property; censorship; sabotage; espionage; and National Security Act and Regulations.

This series also contains staff files of employees of the security service during 1939 - 1945.
Inwards correspondence registration cards, AP589/16, indicate that the majority of these records were transferred to ASIO in 1958.