Our contribution investigates long-term shifts in skill demand in Switzerland with respect to both the level of formal skills and the type of occupational certificate. The former represents the most obvious 'vertical' dimension of changing job requirements, whereas the latter, no less important in a highly segmented labor market, reflects the 'horizontal' differentiation along occupational lines. We argue that two sources are responsible for any change in the aggregate composition of skill demand: The shifting sectoral composition of the economy and the intra-sectoral adaptations related to new technologies and the changing work organization. Against this background, we assess the relative impact of inter-and intra-sectoral change on the long-term trends in skill demand. We apply novel indicators of technological change within sectors to account for the latter. The empirical analyses are based on a representative random sample of job ads published between 1950 and the year 2000 in the German-speaking part of Switzerland.