This study examines the mediating impact of ambidexterity on the relationship between product development proficiency and newproduct performance. Using survey data from 253 Taiwanese firms, the results indicate that the significance of the direct effect of marketing proficiency and technical proficiency on new product performance is reduced when the indirect effect of marketing proficiency and technical proficiency through ambidexterity is included in themodel. Consequently, ambidexterity reflecting the interaction between exploitation and exploration plays amediating role explaining the positive relationship between product development proficiency and new product performance. Managerial implications and future research directions are discussed