Changes of performance monitoring during and after learning of stimulus-response (S-R) associations were examined in younger and older adults using event-related brain potentials (ERPs). To determine whether age-related differences in performance monitoring are attenuated when learning performance is equalized between age groups, participants learned S-R associations until they reached a learning criterion. After completed learning, time pressure was introduced to assess whether time pressure pronounces age-related differences in performance monitoring. In the initial learning phase, performance monitoring was unspecific, indicated by similar-sized ERN/Ne (error-related/error negativity) and CRN (correct response-related negativity) amplitudes. With advanced learning, ERN/Ne and CRN amplitudes dissociated in younger participants, suggesting error-specific performance monitoring, whereas in older participants, performance monitoring remained unspecific. However, after completed learning and under time pressure, larger ERN/Ne than CRN amplitudes were observed in older participants, too. This finding suggests that error-specific performance monitoring develops with learning in younger, but not necessarily in older adults. The administration of time pressure seemed to force older adults to monitor error responses more specifically.