One of the interesting phenomena evidenced by a rough comparison of the 195 ljUigU26!Juensuses-of Pakistan is that the proportion of the population in the labour force has increased from 30.7 per cent to 32.6 per cent. This is surprising from the demographic point of view, since it is well known that under the mortality and fertility conditions extant in Pakistan the likelihood of a proportionate increase in available supply of manpower is low [l]1. Specifically, with a high fertility rate the proportion of the population available as manpower will be low [2; 2a]. Mortality improvements from a high initial level of mortality typically make a population still younger and reduce the proportion at working age. Thus it is unusual that the comparison of the 1951 and 1961 Censuses would indicate an increase in the proportionate size of the labour force of Pakistan, since mor¬tality has been declining in Pakistan and there is no evidence that fertility has declined.