They like a well-drained soil with lots of peat moss and sand. These plants do not like direct sunlight. A bright north or east facing window is best. Keep the soil moist, never soggy and let it dry out between waterings. Be vigilant with the watering, though.
Spathiphyllums are thirsty plants.
The foliage begins to wilt very quickly when they dry out. They will recover rapidly once you water them. A plant that becomes too dry will turn yellow. Peace Lillies love to sit on a tray of wet pebbles. That extra humidity will produce the maximum amount of blooms.