The attire of a mariachi group also defines this type of band. Although many variations have been tried, it has remained the required dress. Early groups many times did not wear uniforms and even today they sometimes wear regional costumes instead of the charro outfit. The most important part of this unique ensemble is the musicians and the music. Mariachi musicians must have certain traits in order to consider themselves as such.
Gender is an issue which is widely discussed today.
In Mexico, only males are normally allowed to be part of a mariachi group. In the U.S. however, females commonly perform in mariachi bands. Mariachi musicians of today are required to read music, play by ear, sing, transpose and improvise invariably when performing unfamiliar songs, all without thinking twice about it. Finally, the music and style define what mariachi really is . Mariachi groups have an almost universal repertoire.