Self-destructiveness can be viewed in two ways: as performing an act which one knows cognitively is not conducive to one's welfare but nonetheless leads to some pleasurable affect (e.g., overeating, smoking); or not performing an act one knows one should perform but which has some negative affective consequences (e.g., dental checkups, saving money). While there is no proof that self-destructive behaviors are interrelated, research in such areas as risk-taking, non-compliance with medical treatment, inability to delay gratification, and preference for delayed punishment indicates the possibility of some relationship. Since individual differences in such tendencies constitute a personality dimension of potential interest, an instrument is needed to identify a generalized syndrome of chronic self-destructiveness. With 12 samplings totaling 803 subjects, a 73-item measure of chronic self-destructiveness was developed and evaluated in a series of reliability and construct validity studies. Reliability of internal consistency was established with alpha coefficients ranging from .73 to .97, and a test-retest consistency ranging from .90 to .98. Chronic self-destructiveness was found to be positively related to external locus of control, negatively related to Type A coronary-prone behavior, and unrelated to need for achievement. (The instrument and scoring key, and a figure depicting the theoretical components of chronic self-destructiveness are included.) (DPO)