Some of the findings of a study investigating careers officers' use of theoretical models in the careers guidance interview are discussed. Data were collected through visits to institutions offering Diploma in Careers Guidance courses, a large-scale questionnaire survey of careers officers, and semi-structured interviews and group discussions. There was evidence that in initial training, theory is used to support, rather than determine, the development of skills. Results also suggested that practising careers officers are familiar with a fairly wide range of theories, although in their interviewing they tend to apply broad principles of theory, rather than specific elements. Careers officers who trained some time ago were less familiar with theories than were those who trained more recently, and there was no support for the hypothesis that long service leads to a greater recognition of the relevance of theories generally. Familiarity with guidance and counselling theories appears to be more influential than knowledge of career theories on the way careers officers think about interviewing. Overall, the findings cast doubt on the view that careers guidance is an applied science.