The composition of the working-age population can influence aggregate employment and average productivity because both employment rates and productivity levels vary across population groups. This chapter assesses the quantitative importance of the working-age population broken down by age, gender and education in explaining differences in employment and productivity levels across countries. Differences in population structure are found to contribute importantly to variations in both labour utilisation and productivity performances. Combining these mechanical effects, differences in the composition of the workingage population account for around a third of the gap in GDP per capita for Europe (EU15) relative to the United States, mainly due to differences in educational attainment.