Introduction Between 1959, the post-war low-point, and 1970, the final year of the old divorce law, the annual number of petitions for legal termination of marriage in England and Wales almost trebled, and the rate more than doubled. The absolute rise was from 26,000 petitions in 1959 to 72,000 petitions in 1970, and the trend, if anything, was tending to steepen rather than to decline. Even at 1970 rates some four and a half million adults will experience divorce during the remaining three decades of this century, more than twice the number of those with such experience in the previous 100 years. Such figures depict a contemporary mass phenomenon of considerable social importance, and some observers have deduced from them a substantial decline in the stability of marriage. Unless, however, marital stability is to be measured by the mere maintenance of the legal tie, such a conclusion goes somewhat beyond existing evidence. Marital breakdown is a complex entity which, for reasons relating both to definition and recording, is not currently susceptible to accurate quantification. Divorce is but one course of action open to those whose marriages fail, and it is not known how far divorce statistics may serve as an index of marital disruption.