This paper presents an exploratory research on the application of the Technology Acceptance Model(TAM) to the domain of object orientation to investigate the validity of TAM in the perspective of its causal relationships. In the Management Information Systems(MIS) area, TAM has been applied to computer usage behavior as a specific technology adoption model. This paper also suggests the factors that affect the technology acceptance of object orientation in U.S. organizations through a modified TAM. Two major research questions are addressed. First, this research investigates the effect of these external variables on the dependent variable, the actual usage of object orientation in the viewpoint of knowledge interaction between structured methods and object orientation. Second, is TAM valid for the technology acceptance of object orientation in terms of its causal relationships? This study empirically explores the impact of the external variables on the level of actual usage of object orientation via the mediating variables in TAM. A structured questionnaire is administered to Data Processing Management Association(DPMA) professionals in US. The result of this study reveals one important contradictory finding that is not consistent with expectations based on related theory. TAM does not accommodate the technology acceptance of object orientation perhaps because object orientation is a complex and organization-level adoptive technology or the measures for the mediating constructs in TAM may not be appropriate in industry settings.