Concert etiquette refers to a set of social norms observed by those attending musical performances. These norms vary depending upon the type of music performance and can be stringent, with dress codes and conduct rules, or relaxed and informal. The rules or expectations for concert etiquette may be informally communicated by word-of-mouth by attendees or participants or they may be printed on tickets or signs.

At classical music concerts, the cardinal principle is to let others listen to the music undisturbed. Instruments and voices are typically unamplified, and the music is rich in detail and includes passages played very softly. Many audience members want to hear everything, and the normal standard of courtesy is simply to be entirely silent while the music is playing. Thus, during this time experienced concertgoers avoid conversation, try to suppress coughs and sneezes, muffling these with handkerchiefs. Electronic devices are turned off. Concertgoers try to arrive and take seats before the music begins; late arrivals wait until a break between pieces allows seating by an usher.

Dress expectations for the audience are today rather informal in English-speaking countries. Audiences usually meet "smart casual" standards, with some performance companies explicitly telling audiences to wear whatever makes them comfortable. Hats are removed as they block others' view of the stage. Dress expectations may still be very formal for special events, events that are difficult to attend, or that take place in traditional venues. Additionally, concertgoers are expected to dress more formally in certain countries than in others.

Concert etiquette has, like the music, evolved over time. Late eighteenth-century composers such as Mozart expected that people would talk, particularly when audience members took dinner (which many had served during the performance), and took delight in audiences clapping at once in response to a nice musical effect. Individual movements were encored in response to audience applause. Robert Bedont notes that “Mozart...would have expected food, drink, gossip, and a rowdy 18th-century crowd.”

The nineteenth century brought a shift in venue from aristocratic gatherings to public concerts along with works featuring an unprecedentedly wide dynamic range. Mahler clamped down on claques paid to applaud a particular performer, and specified in the score of his Kindertotenlieder that its movements should not be punctuated by applause.

With the arrival of recording technology in the twentieth century, applause between the movements of a symphony or suite came to be regarded as a distraction from the momentum and unity of a work. Bedont states that “...with Wagner and Mahler insisting on attentive listening and the background silence of 20th-century recording studios, audience noise has come to be viewed as intrusive to the performers and patrons alike.”

In the 2020s, applause between movements is usually considered something of a faux pas, though a minor and well-meaning one.

Sacred works offered as worship are not applauded. Such works include settings of requiem, Passion, mass, or Kaddish prayer. Presented in an artistic context, such works, along with secular works of comparable gravity, still often get respectful silence for a long moment before any applause.