This paper reports on the theoretical development and empirical validation of a measurement instrument for three IT core capabilities in an electronic commerce context. The instrument is based on the work of Feeny and Willcocks and includes the capabilities “IS/IT governance,” “business system thinking,” and “relationship building.” It was validated using a sample consisting of 179 respondents, all IT managers or CIOs. Results demonstrate that the constructs are reliable (alpha coefficients > 0.8) and valid. A confirmatory factor analysis on the data set yields a moderately acceptable model fit. The model also demonstrates highly significant factor loadings (p < 0.001). We show that a respecification of a competing model in which “IS/IT governance” is split into “business IT strategic thinking” and “IT management” provides better measures of fit. The paper concludes that core capabilities of IT departments are useful constructs to incorporate in future research. They are able to successfully predict behaviors that have relatively little overlap. Recommended further research includes the relationship between capabilities and governance structures, as well as further investigation into how IT core capabilities are formed and strengthened in organizations.