This chapter explores in-depth interviewing, a widely used method in qualitative research aimed at building a depth of understanding, rather than factual or abstract information. We give a brief account of structured interviews, but these have more in common with surveys and questionnaires than in-depth interviewing. Semi-structured interviews are interviews that follow a set of questions, allowing some flexibility in how questions are asked, and provide the researcher with the opportunity to ask clarifying and follow-up questions. Unstructured interviews are more flexible and open-ended. As such, they can be quite unpredictable and varied and are well suited to exploratory research and other research interested in meaning and experiences. There is a range of ethical considerations when using this method, including confidentiality establishing clear and reasonable expectations and offering appropriate reciprocity to research participants, and the potential of this method to cause harm, to both researcher and participants. In-depth interviewing is a powerful but demanding method for urban research; it is resource intensive and requires a lot of skills on the part of the researcher to design effective and ethical protocols and to generate meaning from complex, often messy, data.