International audience ; This study mapped the changes in the timing of working hours in Belgium as reported in workers' daily work schedules, obtained from the Belgian of 1966 and 1999. A typology of working schedules was drawn up by means of a sequence analysis. This approach showed that work performed beyond the standard times, that is, in the evening, at night, or on weekends, did not grow in importance in the intervening years. In 1999, standard working hours clearly accounted for a larger share of the work schedules of the active population. Although the analyses did certainly not corroborate the often alleged trend towards a 24-hour society in Belgium, it could be shown that certain categories of the working population are more susceptible to flexible working hours than others.