There are a few ways to gain membership in Ordo Templi Orientis and Eleusis Encampment: affiliate with the local body or O.T.O. and through initiation.
The first step is making contact with the local body in your area, such as Eleusis Encampment. Attending meet ups, workshops, lectures, or rituals is important in establishing a connection face to face to get to know the local Thelemites in your area, especially if you plan to initiate with the O.T.O.. The O.T.O. is a fraternal spiritual organization, not a teaching order, however, many opportunities in the community arise for members and affiliates to learn and discuss magickal techniques and esoteric topics. While it is not necessary or required for any member of the O.T.O. to actively engage in local events or become members of the local body, it is encouraged to take advantage of what the local body is offering in service to it’s community. It also will help in seeking out sponsors for initiations.
The second step is to consider either taking the path of initiation into the O.T.O., if it aligns with your Will, or to become an affiliated member with the local body without initiation. Eleusis Encampment offers events open to the public so that affiliated members can still benefit from attending. Further, if you choose at the present time, the O.T.O. welcomes Corresponding Associates. Corresponding Associates may attend some O.T.O. events and correspond with O.T.O. members. More about this can be found on the U.S. Grand Lodge page under membership.
If you decide to take the path of initiation into the Order, you must be a free (not incarcerated, on probation, or under any legal authority that might restrict your personal freedom), at least 18 years old, and of good report, which means gaining two sponsors who are of at least I° initiates. Sponsors will want to get to know you before signing the application, so attending local events at the body is important. The introductory initiation into the O.T.O. is called the “Minerval” or 0°. At the Minerval degree, you are then welcomed as an “honored guest”, instead of a full member of the O.T.O.. At this degree the aspirant will decide whether or not to pursue full membership. Minervals are also permitted to begin the preliminary novitiate training under an E.G.C. Bishop towards ultimate ordination as Diaconate and/or Priesthood, which occurs later on in the path of initiation. Minervals are not eligible to become an officer of the local body.
Once the above has been completed, talk with the local body master about your intention of either an affiliated member or taking initiation. The local body master will provide an application and discuss with you any other details such as dues and fees for taking initiation or becoming an affiliate.
More about initiations in the O.T.O. can be found on the Initiation page of the U.S. Grand Lodge website.