Promise Credit Union's mission is to provide financial services mostly to low income families and individuals to help them become financially self-sufficient and to assimilate the unbanked population into the financial mainstream Promise Credit Union's field of membership include those who live, work, and worship within the 14 specific zip codes in Harris County, Texas The zip codes are 77036-77074-77081-77003-77011-77020-77023-77034-77502-77504-77587-77033-77061-77087