By Michelle O’Reilly and Nikki Kiyimba In this chapter from the book Advanced Qualitative Research: A Guide to Using Theory, authors Michelle O’Reilly and Nikki Kiyimba, both of the University of Leicester, examine the distinction between primary and secondary data, a distinction that they regard as overly simplistic and misleading. In order to clarify this particular aspect of the debate we differentiate the different kinds of data as they relate to qualitative research. From this platform a critical discussion of the parameters of secondary analysis is given. Within this discussion they consider the potential differences between reuse of one’s own data and secondary analysis. This requires us to investigate the fundamental issues of context, quality and ethics. The chapter concludes with consideration of the costs and benefits of archiving qualitative data for the purposes of secondary analysis.