Over the past thirty-five years I have been devising theoretical models for psychosomatic medicine and conducting research on alexithymia and emotion regulation. During the 1980's I advanced a dysregulation model of disease, which was based on a synthesis of contemporary psychoanalytic ideas and observations with recent findings from neurobiology and developmental psychobiology. My research has focused on one component in this model, namely, deficits in the cognitive processing and regulation of emotions. My colleagues and I developed the self-report Toronto Alexithymia Scale (TAS) and an improved twenty-item version (the TAS-20), and conducted a series of studies which yielded considerable empirical support for the validity of the alexithymia construct. We also investigated the relationship between alexithymia and certain medical and psychiatric illnesses, which we have conceptualized as disorders of affect regulation. In other studies, we have investigated relations between alexithymia and emotional intelligence and the five factor model of personality; we have also collaborated with colleagues in some experimental studies which examined relations between alexithymia and various aspects of emotional processing. More recently we developed the Toronto Structured Interview for Alexithymia (TSIA); the reliability and validity of this instrument have been demonstrated in Dutch, German, and Italian translations of the instrument.