This study seeks to identify the unwritten rules and standards of professional conduct followed by the music community. Its central source of information is a pair of surveys sent to professional musicians, specifically members of large instrumental ensembles across the United States. The first survey posed multiple-choice questions on topics related to personal professional standards, rehearsal and concert etiquette and protocol, and ethical obligations. The second survey followed up with consenting individual participants and requested stories and anecdotes from the respondents’ professional careers. The surveys yielded 70 responses from the initial 350 solicitations, representing 35 professional ensembles in 30 cities and 20 states, 18 different instruments, 41 principal players, and nearly 2,000 combined years of professional music experience. The findings shed light on many specific aspects of professionalism in the music community, and they demonstrate that an unwritten code of largely understood and observed expectations both exists and varies minimally throughout professional ensembles across the United States. The consummate professional musician is prompt, prepared, and observant of an array of expectations generated by the routines and hierarchies of rehearsals and concerts. Understanding the professional attributes and practices of successful ensemble members is important to aspiring musicians, and so this study is intended as a useful resource both for students and their teachers.