The desired number of children is a measure used to forecast fertility that has been known for a long time and is a subject of contention. It can be regarded as certain that it provides information on fundamental willingness to have children. This willingness has fallen in the last 15 years, and in particular the desire to remain childless has increased. On the whole, it is possible to observe a polarisation phenomenon which corresponds to actual reproductive behaviour and is stronger in the old Federal Länder than in the new. If one investigates the determinants of the desired number of children, first of all the influence of sociodemographic factors, known from research literature, is confirmed. Added to this is the major influence of individual orientations and values, above all a positive attitude towards partnership and children will enhance the desired number of children, whilst self-realisation efforts, the desire for an equal partnership or concerns about prosperity will tend to prevent it. Finally, one can see a connection between the desired number of children and the assessment of family policy measures such that it is only with desiring to have children that potential parents examine the environment for parenting. If this situation arises, above all financial measures and more flexible working hours arrangements are favoured.