The initial By-Laws provided for three types of membership: Honorary, Charter and Regular. Honorary membership would be reserved for certain former Directors of OSI and/or any other person deemed worthy of such honor. They would be exempt from any dues. Charter memberships were for those persons who joined during the period 1 May 66 to 30 June 67. After 1 July 67, active duty Special Agents who applied within 90 days of their leaving duty as Special Agents could be given such status. (The Charter category was eliminated with the 1 July 84 edition of the By-Laws.) Regular memberships were available to all others who met the membership criteria.
An Associate category was introduced on 1 April 1973 by Amendment #1 to the By-Laws for either the wife or spouse of a deceased member or a person who was formerly assigned to or employed by OSI in a capacity other than as a Special Agent. An Associate Member could neither hold office nor vote in the Association. Annual dues were, in effect, one-half of a regular member's dues until 1992 when a US Postal Service regulation required the Association cover costs with all dues. A By-Laws change in 1995 authorized administrative/support personnel to opt for the Regular category of membership.
The Affiliate membership category was promulgated in the 1 Jul 84 edition of the By-Laws for persons actively serving as military or civilian Special Agents for AFOSI, although they were restricted from holding office or voting. This category was established after the Commander, AFOSI determined there was no apparent conflict in their membership. With the coming into effect of the November 1989 edition of the By-Laws, the membership categories were streamlined by placing all Affiliate Members in the Regular category and removing the restrictions. Additionally, all Honorary Members who were eligible for Regular membership were given all the rights and privileges of such membership, but still remaining exempt from annual dues payment.