Previous research has assessed the effect of L1 experience on the categorization and production of L2 stops. However, the effect of L2 experience on the L1 has received much less attention. In addition, no previous studies have tested the same population on both perception and production and using modified natural stimuli. The present paper attempts to determine the effect of L2 experience on the perception and production of L1 Spanish and L2 English bilabial stops. A categorization task as well as a production task in each language was completed by experienced and inexperienced Spanish learners of English. Experienced learners were found to perceive and produce L2 bilabial stops more accurately than inexperienced learners, although such difference reached significance only in perception. As for L2 influence on the L1, experienced learners differed from inexperienced learners in the Spanish identification task. Nevertheless, no significant effect of experience was found in production. Moreover, experienced learners were found to categorize bilabials differently in each language, whereas inexperienced learners were not. Further, both groups seemed to produce L1 and L2 /p/ differently yet English and Spanish /b/ were produced with Spanish-like values. Finally, no relation between individual perception and production was observed.