Tests measuring the coronary-prone Type A behavior pattern, anxiety, and neuroticism were administered to 95 male patients undergoing coronary angiography. Item analyses suggest that men with more serious coronary atherosclerosis are hard-driving, hard-working Type A individuals who put pressure on themselves to solve problems, meet deadlines, and to move up the social ladder. At the same time, these patients are often uncomfortable in their interpersonal relationships and they feel awkward and insecure when in groups. They obtain their rewards in life from seeking achievement rather than from socializing with people. They seem to have a low threshold for becoming tense or depressed. The present study suggests that the combination of these two sets of essentially independent psychological characteristics, Type A behavior and social insecurity, portends a greater severity of atherosclerosis than the possession of either single characteristic alone.Studies from many parts of the world have now replicated earlier findings that at least two clusters of psychological variables are associated with the presence of coronary heart disease (Jenkins, 1971(Jenkins, , 1976. The first such variable is the coronary-prone behavior pattern, Type A-an overt style of behavior that is hard driving, competitive, impatient, hurried, aggressive, and intensely committed to vocational goals. The social psychological properties of the Type A pattern have recently been summarized by Glass (1977). This behavior pattern can be measured either through a structured interview (Rosenman, et al., 1964) or through a self-administered computer-scored test, the Jenkins Activity Survey (JAS; Jenkins, Rosenman, & Friedman, 1967). Each of these methods has been shown to be associated with coronary heart disease prevalence, incidence, and with recurrence of myocardial infarction (Jenkins, 1971(Jenkins, , 1976.