This article, the sixth in a series aiming to provide practical guidance for qualitative research in primary care, introduces two approaches for addressing longitudinal and complex health themes in primary care research. The first approach - longitudinal qualitative research - supports the study of change during the life course. The second approach - mixed-methods research - integrates quantitative and qualitative research to gain new insights to address the complex and multifaceted themes in primary care.We discuss the context, what, why, when and how of these approaches and their main practical and methodological challenges. We provide examples of empirical studies using these approaches and sources for further reading.
