This article examines the determinants of multiple job holding in the UK. We address these issues using data from the first 11 waves of the British Household Panel Survey (BHPS), which covered the period from 1991 to 2001. Evidence from the BHPS does not support the hypotheses of main job hours constrained and main job insecurity. We argue that the incentive for moonlighting in the UK is due to financial pressures and the desire for heterogeneous jobs. The empirical work is carried out separately for men and women.