Up to now it has been difficult to study fear of childbirth because of a shortage of adequate psychological measurements. Therefore the Wijma Delivery Expectancy/ Experience Questionnaire (W-DEQ) was developed. This paper presents the theoretical background of the W-DEQ together with a documentation of the first psychometric studies. Examination of construct validity indicates that it seems to be possible to penetrate a psychological construct related to fear of childbirth by means of the W-DEQ, both before and after delivery, in nulliparous as well as in parous women. The questionnaire measures the construct more clearly in parous than in nulliparous women. Internal consistency reliability and split-half reliability of the W-DEQ of > or = 0.87 are good for a new research instrument. More research is on its way to make the W-DEQ suitable even for measurements in applied settings.