Development and validation of a revised measure of Adlerian social interest

The Social Interest Index (SII; Greever, Tseng, & Friedland, 1973) is the most frequently used measure of Adler's (1964) most important personality trait, and recent research has suggested that it may be the most valid among social interest measures available to researchers and therapists (Bass, Curlette, Kern, & McWilliams, 2002). Nevertheless, the SII has been criticized for key aspects of its construct validity (i.e., content validity and factorial validity). It was the purpose of this research to offer researchers a dramatically shortened version of the SII by eliminating poor items and yet without a loss in reliability or criterion validity. Several studies resulted in an 11-item short form of the SII that retains the scale's desirable psychometric qualities.