The Life Style Index (LSI; Plutchik, Kellerman, & Conte, 1979 ) was designed to assess defense mechanisms, assuming that their use is related to specific affective states and diagnostic concepts. We aimed to assess the psychometric properties of its Greek version and its relation to psychopathological symptoms. The LSI was back-translated into Greek and was administered to 1,261 participants. Six factors were identified, 5 of them largely corresponding to the original version's defenses (compensation, denial, projection, reaction formation, and repression). The sixth factor, named regressive emotionality, included mainly the original scale's regression and displacement factors. Test-retest reliabilities, internal consistencies, and construct validity were quite satisfactory. Most defenses were able to discriminate psychiatric patients from healthy participants and were associated with specific psychopathological symptoms in a theoretically expected mode, further supporting the validity of the Greek version. Our findings suggest that the LSI, based on both psychoevolutionary and psychoanalytic theory, can provide a solid ground for assessing ego defense mechanisms.