A mission president is responsible for the spiritual and physical well-being of the missionaries who serve under his authority. He must make sure that the housing and food provided for missionaries is clean, safe, and adequate. A system is provided for the medical care of missionaries in case of ill health or accident.
Missions are divided into zones with a certain number of missionaries in each zone. Missionaries are assigned to certain neighborhoods or areas according to the stakes or districts that cover that zone. The mission president assigns missionaries to companionships—missionaries serve in pairs. Transfers of individual missionaries from one area to another or one companionship to another are also made by the mission president.
Every six weeks, some missionaries finish their service and new missionaries arrive. The mission president interviews the departing missionaries—an important part of missionary work is the personal growth of the missionary himself. The mission president and his wife welcome the new missionaries and orient them to the mission.
The mission president travels to and presides over zone conferences. Missionary principles are reviewed through a variety of classes. Testimonies are often born.
It is not uncommon to hear references to both a husband and wife serving as mission presidents. This is, however, is incorrect as only a high priest may serve as mission president. The mission president's wife is set apart as a missionary and a companion to her husband and accompanies him to his field of service.
Mission presidents' wives have choices in how they serve. Since mission presidents can bring their children with them (if they are still dependent), some mission presidents' wives are still very busy with the duties of motherhood. Mission presidents' wives with young children normally have less time to interact with the missionaries or to serve in leadership capacities. Those with more time are able to travel to conferences, speak at conferences, teach, participate in musical presentations, orient new missionaries, and host gatherings.
Mission presidents leave their vocations and their homes for a period of three years. It can be a challenge to restart a vocation after such an absence. Therefore, it is an advantage for a mission president to have his financial affairs in good order. Mission presidents and their wives must also have the health and strength necessary to serve. Some couples are assigned to areas without a high standard of medical care, or even to areas where the basic standard of living is very low.