The purpose of the present study was to examine the nature of a social desirability measure under two different types of instructions for filling out personality questionnaires in an occupational selection setting. 1230 male applicants for public vehicle driving licences were administered Cattett's 16PF and the Eysenck Personality Questionnaire (EPQ). The subjects were randomly assigned to two groups. One was given standard instructions for filling out these questionnaires; the second was given special instructions designed to reduce social desirability response bias. Social desirability was indexed by the Lie scale of the EPQ. Based on Eysenck's theorizing concerning the meaning of the Lie scale, the following hypothesis was tested: the factorial location of the Lie scale in the personality domain will differ under the two forms of instructions. It should appear separately from other personality factors under the standard instructions, whereas under the special instructions it should be subsumed under the personality factor which measures conformity. The results supported this hypothesis. The discussion focuses on the meaning of the Lie scale under conditions that elicit social desirability bias and on the role of special instructions in reducing this bias.