Using longitudinal data from 8 surveys on attitude change in the Netherlands, I tried to clarify trends in sexual permissiveness since the 1960s. In explaining these changes, time-period effects proved most important, whereas cohort replacement appeared to be of minor significance. Hence, changing attitudes toward permissiveness are best understood in terms of structural developments (period effects) through which everybody in society is affected. Furthermore, this study found that churches are successful in keeping their members from developing progressive opinions. With respect to age, the growing-conservative-when-growing-older argument also holds for sexual permissiveness. A description of gender-specific trends revealed that gender differences were relatively constant over time. Only with respect to ‘sex before marriage in a stable relationship’, was a convergence of the gap established.