The use of codebooks to categorise qualitative data and to increase consistency in coding between multiple researchers is a well-established strategy in qualitative research. However, due to the focus on team-based research projects, the possibilities for the use of codebooks by individual researchers are rarely discussed. With the aim of adding to current literature and practices on the use of codebooks, this article describes, following a personal narrative style, the process and explores the benefits and challenges of developing a codebook for the analysis of qualitative data by an individual researcher. Starting from a set of transcripts from interviews with undergraduate students completing a one-year work-placement, it describes how developing and using a codebook was instrumental in improving the rigour of data analysis, and in supporting data theorisation and reflection on a research project exploring transfer of learning between university and the workplace. The approach and discussions presented here will be useful to qualitative researchers looking for a systematic method for the development of a codebook, but also for researchers working independently on the analysis of qualitative data.