In this chapter we discuss the development of part-time work in Finland and Norway and ask if there is a trend towards more marginalised part-time work also in the well-regulated Nordic labour markets. Furthermore, we investigate if there are differences between Norway, with its long tradition for normalised part-time jobs among women, and Finland, where full-time work has been the normal choice for women. Part-time jobs are more common among young persons, women, and in the service sectors. In both countries, part-time jobs are more insecure than full-time jobs. However, there is no strong tendency towards more insecure part-time jobs over time. We also examine mobility from part-time jobs to other positions in the labour market. In both countries, part-time work is characterised by high stability. Hence, the results do not give support for increased polarisation in terms of increased work insecurity among part-time employees. in terms of increased work insecurity among part-time employees.