Managers of sales units aim to accomplish organic growth by acquiring new customers while retaining their existing ones. Although customer acquisition and retention are complementary goals, they involve managing conflicting sales tasks. Firms that succeed in effectively combining these conflicting tasks are “ambidextrous”. Based on three current sources, (1) the resource-based view, (2) the literature on ambidexterity, and (3) the Motivation-Opportunity-Ability framework for work performance the authors identify a set of organizational capabilities contributing to a sales unit’s ambidexterity. Survey and archival performance data related to 208 firms provide an empirical test of the conceptual model and hypotheses developed. Results confirm that the identified capabilities, and several of their interactions, make sales units more ambidextrous. Sales unit ambidexterity then significantly increases a firm’s sales growth rate and profits, but reduces Return on Equity slightly.