The present overview on existing research addresses the double implication of working-time standards as legal (or contractual) norms, on the one hand, and socially established normality, on the other. Looking primarily at the evidence on the statutory 35-hour week in France, the author discusses the question of how changes in norms as stipulated by law or collective agreements may affect working-time practices in the society. Given the specific institutional and policy tradition of statist intervention in France, a comparison with the effects of the contractual 35-hour week on actual hours in the West German metal industry highlights particular strengths and weaknesses of the French approach. While the empirical evidence underscores the crucial importance of statutory norms and the interaction between governments and social actors, it equally reveals the increasing difficulties to set limits to normal hours for growing shares of the workforce just by setting statutory or collective norms. The transformation of new working-time norms into normality leading to a generalized shorter standard workweek is a long-term social process that requires continual intervention of actors at various levels and must be embedded in agreements both at the workplace and within households.