That family reconstitution can provide demographic information of the greatest precision and detail is not in question: nor that parish registers can provide suitable source material. Henry, indeed, perfected the method and then applied it to historical material out of frustration over the quality of contemporary sources of information suitable for the study of the fundamental characteristics of fertility and fecundity. His study of Crulai, the first application of the technique to a parish register, was a landmark in the development of historical demography.

In a closed community which kept complete records of all births, deaths, and marriages, it would be possible in principle to describe and analyse any aspect of demographic behaviour exhaustively. No such community has ever existed, but the standard of ecclesiastical record keeping was sometimes very high in pre-industrial Europe, and the rules of reconstitution, by defining the periods during which an individual may properly be regarded as in observation for each type of demographic measure, largely overcome any difficulties arising from the fact that high levels of migration left most parishes very far from being closed communities.

The most unimpeachable method for concatenating information taken from baptism, burial, and marriage registers into individual life histories, however, may nonetheless fail to produce any useful results if the source to which it is applied is seriously defective. Anglican registers have a number of well-known weaknesses that may affect the accuracy or completeness of reconstitution.