While music listening on mobile phones can serve many affect-regulatory goals, success in reaching these goals is yet to be empirically assessed. This study aimed to determine how frequently listeners successfully reach their affect-regulatory goals, and the predictors of this success. Data were collected using the experience sampling app MuPsych, from 293 Finnish participants. Goals were successfully reached in less than half of cases, with adults more successful than adolescents. Success was determined largely within contexts, and strongly predicted by an initial low-valenced emotional state of the listener, suggesting that music listening is particularly useful for those in negative states.