The acquisition of acrophobia in a large clinical sample was investigated. 148 patients from a university-based height phobia clinic and 148 age and sex matched non-phobic controls served as Ss. Subjects were assessed with a battery of measures including the Acrophobia Questionnaire [Cohen, D. C. (1977), Behavior Therapy, 18, 17-23], self-rating of severity [Marks, I.M. & Mathews, A. M. (1979) Behaviour Research and Therapy, 17, 263-267] global rating of severity [Michelson, L. (1986), Behaviour Research and Therapy, 24, 263-275], origins questionnaire [Menzies, R. G. & Clarke, J. C. (1993a) Behaviour Research and Therapy, 31, 355-365], and a height avoidance test. Results obtained question the significance of simple associative-learning events in the acquisition of fear of heights. Only 11.5% of fearful Ss were classified as directly conditioned cases. Furthermore, no differences between groups were found in the proportion of Ss who knew other height-fearfuls, had experienced relevant associative-learning events, or the ages at which these events had occurred. Finally, no relationships between mode of acquisition and severity or individual response patterns were obtained. In general, the data were consistent with the non-associative, Darwinian accounts of fear acquisition that continue to attract theorists from a variety of backgrounds [e.g. Bowlby, J. (1975) Attachment and Loss; Clarke, J.C. & Jackson, J. A. (1983) Hypnosis and behavior therapy: the treatment of anxiety and phobia; Marks, I. M. (1987) Fears, phobias and rituals: panic, anxiety and their disorders; Menzies, R. G. & Clarke, J. C. (1993a), (1993b) Behaviour Research and Therapy, 31, 499-501; Menzies, R. G. & Clarke, J. C. (1995)].