Three samples consisting of normal adults (n=182), psychiatric patients (n=352) and high school students (n=1,485) were used to evaluate the empirical item structure of the Basic Personality Inventory. Using a principal components model with a confirmatory rotation, 96, 99, and 98 percent of the items loaded appropriately on their respective scales. No items were found to load inappropriately across all three samples, 219 of 220 items loaded appropriately across two samples, and 205 of 220 items loaded appropriately across all three samples. The empirical item structure was found to be congruent with the hypothesized structure, with keyed items showing much higher loadings than non-keyed items. All results indicated a substantial improvement over that expected by chance. These results were interpreted as providing evidence for the efficiency of the construct-oriented heuristic.