The strategy of family planning programmes is that increasing the knowledge, acceptance and availability of family limitation methods will lead through increased use to the reduction of aggregate fertility levels. At the same time, many of the countries that have introduced programmes have also been undergoing socio-economic change which raises the question of partitioning the credit for any decreases in fertility between the programme and modernizing factors, such as increasing levels of education and decreasing child mortality. One way of testing for a programme effect is to determine whether among the geographical areas within a country there is a relationship between levels of fertility and programme factors, after taking into account socio-economic and demographic factors also thought to influence fertility. This approach to the study of family planning programme effects on fertility may be termed “a real multi- variate analysis” and has been employed in several countries often as an adjunct to other methods of evaluation. The purpose of this chapter is to review the rationale of this approach, to point up its advantages and limitations and to provide a detailed example of its application.