A person who arranges a piece of music for a singer, a group of performers or other music ensembles.

His primary role is to arrange a piece of music based on the needs or requirements of a performer, a group of performers, a conductor, producer or music director. The arranger makes sure that every aspect of a music piece is well harmonized, from the instruments down to the tempo. The music that an arranger works on may either be an original or an already existing music piece.

Many music arrangers today have their own music studios equipped with necessary tools of the trade including various musical instruments, synthesizers, computers, plug-ins, software, mixers and microphones. The equipment used usually depends on the arranger's forte and clientele.

Arrangers generally know how to play several instruments, have a good grasp of music theory, able to read and write music, able to transpose and transcribe and have a strong background in orchestration, harmony and composition. A good arranger must be original, creative and adaptive.