The agricultural labour force in Pakistan has been increasing rapidly due to population growth as well as a declining mortality rate. However, the share of the agricultural labour force to total labour force has been decreasing. The objective of this paper is to search for the factors responsible for this decline. The period covered is from 1959•60 to 1986-87. The development process is characterised as one which brings about a fundamental change in the structure of an economy. In this process, labour is shifted from low productivity areas, such as agriculture, to high productivity areas, such as the manufacturing, construction and transport sectors. The share of value added of agriculture in Gross Domestic Product (GDP) has declined from 46 percent in 1959- 60 to 25 percent in 1986-87. Hence, the key determinant of declining share of agricultural labour force to total labour force (RA LF) appears to be some measure of economic development.