Enterprise Systems entail complex organizational interventions. Accurately gauging the impact of any complex information system requires understanding its multidimensionality, and the development of a correspondent, standardized, validated and robust measurement instrument. Despite the popularity and potential of Enterprise Systems in modern organizations, no acceptably valid and reliable Enterprise System success assessment scale has heretofore been developed. The present study tests the reliability and construct validity of the Enterprise System Success (ESS) measurement model and variants, against new empirical data. Results from a confirmatory factor analysis utilizing structural equation modeling techniques confirm the existence of four distinct and individually important dimensions of ESS – Individual Impact, Organisational Impact, System Quality and Information Quality. Based on the analysis of results, the ESS instrument demonstrates strong reliability and validity.