Organs and pianos are the standard instruments used in the Church meetings. If other instruments are used, such as orchestral strings, their use should be in keeping with the spirit of the meeting. Instruments with a prominent or less-worshipful sound, such as most brass and percussion, are not appropriate for sacrament meeting. Careful selection and proper performance of music can greatly enhance the spirit of worship.
Stake presidencies and bishoprics should resolve specific questions about the use of musical instruments in Church meetings.- Church Music Handbook, p. 2