Activity-based costing is widely used in managerial accounting as a cost measurement instrument. Accounting practices can differ widely between countries. Recognizing differences and similarities in seemingly identical practices between countries provides the opportunity for improvement and allows us to draw managerial implications in light of the increasing internationalization of companies. This paper compares US and German activity-based costing. The paper establishes differences based on purpose, cost concepts, construction and cost allocation, and quantity and quality of cost information. It then proceeds by using the Technology Acceptance Model (TAM) to formulate propositions concerning the acceptability of the systems by managerial accountants in the USA and Germany.