Compared to quantitative research, qualitative research has a varying and even troubled relationship with theory (Bendassolli, 2014). Quantitative methods were developed as a means of testing theoretically-derived hypotheses, for example that when x happens, y will occur. Although there are some atheoretical quantitative studies that, for example, investigate the outcome of an intervention, often the theory being tested in a quantitative study is explained when the hypotheses are introduced. However, the position of theory is not always so predictable, or even visible, in qualitative research. Sometimes the aim of the research is to build novel theory, ensuring this is developed from the data, rather than from ideas the researcher has brought to the research. At other times prior theory, or broader theoretical frameworks, play a significant role in framing a qualitative study - guiding data collection and/or analysis. Alternatively, several theoretical concepts might be used selectively to make sense of findings, rather than using the findings to test the theory, as in quantitative research. However, in many of the qualitative papers submitted to JHL, theory makes only a fleeting appearance, if any at all, perhaps being mentioned in passing in a final discussion of where the study fits within the broader literature. A research paper may therefore document in some detail the experiences or views of a particular group of breastfeeding women or those supporting them, without developing a more conceptual understanding of what is going on or how these views might have arisen. Some have argued (e.g. Meyer & Ward, 2014) that theorisation is a key way in which qualitative health researchers’ findings lead to knowledge development and are transferred to different contexts, informing practice. If this is the case, does it matter if qualitative analyses of breastfeeding-related issues are sometimes ‘theory-lite’? Or are there good reasons for qualitative researchers to demonstrate varying levels of engagement with theory and even to be wary of theory? This article will consider these questions in relation to different kinds of theory, different qualitative approaches and varied research purposes related to breastfeeding.