This chapter discusses the epidemiology of infertility and the importance of the initial assessment of the infertile individual. Profound changes in society over the last two decades challenge previously agreed on norms in our understanding of the nature of parenthood and family. Defining infertility in a contemporary context has thus also changed as the profile of those seeking advice has evolved. Nevertheless it remains essential that efficient mechanisms for referral and investigation are established for those involved in the planning of fertility services. These must involve good liaison between primary care providers and medical, nursing and diagnostic laboratory staff in specialist centres. Adherence to agreed on protocols will facilitate appropriate and timely investigation along standardised paths, thereby minimising risk of delay and repetition of tests which those seeking assistance find particularly demoralising. Once a diagnosis is reached it should be possible to offer people with infertility an accurate prognosis and the opportunity to consider the issues relevant to treatment choices for their particular situation.