In two experiments we examined the extent to which musicians identify discrepancies between their intentions and their playing during individual practice. In the first experiment, 60 musicians representing four levels of skill development practiced a familiar piece from their own repertoire for 5 min while being audio recorded. They then listened to their recorded practice and pressed a computer key to mark moments of discrepancy between what they had intended while practicing and what they heard on the recordings. The mean rates of key presses did not differ among the four participant groups, although there were large within-group variances. In the second experiment, 13 high school and 11 expert participants from Experiment 1 returned 2 years later and listened to their original recordings, this time marking moments of discrepancy between what would be their "current" intentions and what they heard on their 2-year-old recordings. High school participants marked significantly more discrepancies after 2 years than they had in Experiment 1, but the mean rate of key presses among experts did not increase between Experiment 1 and Experiment 2. These results support the notion that the precision of performance goals and the acuity of perceptual discrimination are central features of musical expertise.