The Western Diocese consists of all parishes, religious communities, and affiliate bodies located in the Western United States within the state of Alaska, Arizona, California, Colorado, Hawaii, Idaho, montana, Nevada, Oregon, New Mexico, Utah, Washington and Wyoming. The Diocese is presided over by the primate, Archbishop Hovnan Derderian, who is the spiritual father of the communities within the Diocesan family.

Currently the Western Diocese has 50 parishes in the western United States, under the leadership of His Eminence Abp. Hovnan Derderian,primate as the spiritual leader of the Western Diocese and its faitful.