The concertmaster/mistress, (from German Konzertmeister) is the leader of the first violin section of an orchestra. In the UK, the term commonly used is leader. Any violin solo in an orchestral work is played by the concertmaster (except in the case of a concerto, in which case guest soloists may be heard).

The concertmaster makes decisions regarding bowing and other technical details of violin playing for the violins, and sometimes all of the string players; and is in charge of leading the orchestra in tuning before concerts and rehearsals and other technical aspects of orchestra management.

The concertmaster in a standard wind band is the first-chair clarinet, and leads the ensemble's tuning. The first-chair clarinet concertmaster will, in common practice, play all solos for their instrument. Often the lead flautist will receive similar responsibilities to the clarinet concertmaster, depending on several factors such as age, skill and time spent in the ensemble. The concertmaster will, in both orchestral and wind band settings, also coordinate with other principals and section leaders, in most cases being their senior in terms of group pecking order. In brass bands this role is often filled by the principal solo cornet.

The concertmaster has the duty of tuning the orchestra or band at rehearsals and performances, and also comes on stage individually. He or she will walk onto stage prior to performing, take a bow, and receive applause on behalf of the ensemble. However, this practice is usually uncommon in Europe where the concertmaster walks onto stage at first but immediately followed by the remaining orchestra members.^{[citation needed]} Thus the entire ensemble receives applause at the beginning and the concertmaster's role is less individual.

It is usually required that the concertmaster be the most skilled musician in the section, good at learning music quickly, counting and observing the conductor for the rest of the section to follow.