Instruments are robust when their items or constructs have the same meaning across different subgroups or conditions of measurement. If an instrument is not robust, its usage may result in poor managerial decisions or confound the interpretation of research results. Multi-group analysis of factorial invariance provides a rigorous test of whether constructs or individual items have equivalent meanings across sub-groups. Using a sample of 1166 responses, the hypothesized EUCS measurement model is tested in this research for invariance across type of application, platform, mode of development, and position of respondent. The results support the robustness of the 12 items comprising the EUCS instrument.