Norms and sanctions regulating the sexual behavior of the unmarried ha
ve changed in many societies in recent decades, such that significant
numbers of the population, expecially although not exclusively among t
he young, live together openly as unmarried partners. A transition per
iod, characterized by high rates of premarital pregnancies, lasted lon
ger in Norway than in neighboring countries. Below it is suggested tha
t the source of the delay may be found in a cleavage in Norway's socia
l structure. In some regions of the country a pietistic attitude domin
ated, in others a liberal attitude. This was a major axis of Norwegian
politics from the end of the nineteenth century until well into the t
wentieth. Acts of Parliament swung from severe punishment of 'concubin
age', as it was called, to remarkably early laws providing public supp
ort when needed for unwed mothers and their children. Punitive sanctio
ns against illegitimacy were enforced only for a brief period, althoug
h the law remained on the statute books until the 1970s. The signals s
ent to the population were sufficiently mixed as to create a condition
of pluralistic ignorance, inducing more conformity to strict sexual b
ehavior than occurred elsewhere. The most recent investigations provid
e convincing evidence to support the contention that non-marital cohab
itation has now become a civil status accepted by all.