In this paper, the main focus lies on the development and size of the shadow economy labour force in OECD, developing and transition countries. Besides informal employment in the rural and non-rural sector, other measures of informal employment like the share of employees not covered by social security, own account workers or unpaid family workers are also shown. The most influential factors on the shadow labour force are tax policies and state regulation, which, if they rise, increase both. Furthermore the discussion of the recent literature underlines that economic opportunities, the overall situation on the labour market and unemployment are crucial for an understanding of the dynamics of the shadow economy and especially the shadow labour force.