The Southeast Michigan Group (SEMG) Executive Committee (ExCom) is the decision-making body of the group. There are 9 members with two-year terms elected to this committee in an annual year-end election. Five members are elected in one year and four are elected in the next year. The committee can appoint a new member to fill a vacancy in between elections.

Sierra Club members not elected to the Executive Committee can work on ExCom subcommittees. The principal subcommittees are Fundraising, Program, Publication and Treasury. Other subcommittees may be created as needed.