Managers are increasingly being called upon to adopt the strategy-making process known as Entrepreneurial Orientation (EO) to increase their firm’s entrepreneurial activities. EO is a well-researched construct at the firm level-of-analysis, but is only beginning to be explored at the individual level of analysis. This study designed a new Assessment Center (AC) rating instrument of EO at the individual level-of-analysis based on the Bolton and Lane (2012) Individual Entrepreneurial Orientation scale. A construct validation study of the instrument was carried out in a preexisting university AC where 60 archival project management exercises were observed and scored by 4 trained raters divided as pairs into 2 rater conditions. One condition completed the Entrepreneurial (EO) Rating Instrument, whereas the other condition completed a standard managerial rating instrument. Evidence of discriminant validity was established for the 2 dimensions of Innovativeness and Opportunity Recognition. This suggests that ACs may be able to measure EO at the individual level-of-analysis using the Entrepreneurial (EO) Rating Instrument and that standard managerial rating instruments may not be able to fully capture the construct of EO by themselves.