Within the field of clinical psychology, contributors who are both psychoanalysts and leading empirical researchers are increasingly rare. Yet one figure who has made extensive contributions as an analytic clinician, as a researcher, and as a theoretician is Sidney J. Blatt. In addition to being trained as a psychoanalyst, he has conducted extensive research on personality development, psychological assessment, psychopathology, and psychotherapeutic outcomes. Along with his many students and colleagues, he has developed several widely used measures, both self-report and projective, for assessing depressive style, self-and object representations, and boundary disturbances in thought disorder. In short, Sid has been a wide-ranging and productive scholar in a career of more than 40 years' duration, and throughout this career he has been committed to the proposition that it is not only possible but also essential to investigate psychoanalytically derived hypotheses through rigorous empirical science.