The data collected in large surveys provide many advantages for research into the quality of working lives, but there are challenges involved in analysing pre-existing datasets. This chapter focuses on research into paid and unpaid work. It demonstrates how valuable it is to have access to surveys that sample large numbers of workers, sometimes tracking those people over many years of their working lives. Large sample sizes are crucial if a researcher wants to examine the work of sub-groups: to compare them systematically according to variety by gender, ethnicity, class or age, for example. The chapter also outlines the limitations, practical and epistemological, that come with analysing data designed and collected by other researchers. Drawing upon personal experiences of studying part-time jobs, housework and work–life balance, this chapter reflects on the potential of this methodological approach for researchers exploring the quality of our working lives.