In this thesis I analyse sub-national differences in the employment trajectories of mothers of young children in Germany (Bundeslaender) and the UK (Government Office Regions and Metropolitan counties). The thesis combines longitudinal and spatial approaches to paid work, and focuses on mothers of children under 6 - arguably the group at the core of the social (re)production of gender differences in employment. One of its aims is to nuance the existing literature explaining the differences in women's involvement in paid work in terms of national welfare and/or breadwinner regimes - by looking at the nature and extent of regional variations in the patterns of involvement that make these countries typical of such regimes. Its specific goals consist in testing the Latent Growth Curve (LCM) framework as a method for modelling variations in participation in paid work over time, then in exploring three possible explanations for the regional differences observed. The respective role of regional differences in the family formation and social position of the maternal labour force, of the availability of suitable jobs in particular segregated jobs, and finally of economic histories in relation to women's orientations to work is assessed. The results confirmed that LCM represents an innovative tool to understand variations of involvement in paid work over time, and revealed significant regional differences, beyond the 'North South' and 'East-West' divides documented respectively in the UK and Germany. In both countries, results pointed at a combined effect of the three explanatory factors analysed. Whilst composition and labour demands effects went some way towards explaining some of the variations observed, at the same time additional regional variations were discovered once composition factors were taken into account. Finally the pattern of association between the remaining unexplained regional variation and aggregate attitudes of women towards paid work suggests an influence of long term trends in participation on present levels of involvement.