Scientifi c discourses that address ‘work’ as a research subject primarily focus on gainful employment, that is, the sphere of formal work. Informal work has for a long time been regarded as a remnant of precapitalist traditional society which will be eradicated in the ongoing modernisation process of developed societies. We by contrast start with the assumption that the role of informal work is different, that it is the ‘other side’ to formal employment in modern postindustrial society. We argue here that the development of postindustrial society can be adequately analysed only if the relationship and interaction between formal employment and informal work is studied (see also Chapter 1 in this volume).