This paper describes research investigating the perception of intrusive music, that is, music heard when choice, volume, and occurrence are not under the control of the participant. Participants were directed to record diary accounts of episodes in which music was played in instances when they were not in control of the decision to play the music or any characteristic of it, and to record various items about the music, together with any effects on themselves. Strong reactions were discovered during thematic analysis- reactions influencing mood, energy, distractibility, desire to stay or return, and intention to purchase. The implications for commercial use of music are discussed along with the efficacy of the diary method in this context. (Contains 3 figures and 1 footnote.)