There is increasing emphasis on understanding economic advantage alongside disadvantage -- on studying both 'poverty' and 'riches'. This trend prompts and requires new ethical reflection. I argue that in qualitative interview research, a clearer distinction needs to be drawn between ethical commitments to individual research participants, and the group(s) to which they belong. This distinction is often elided in ethics guidelines and when researchers discuss their own work. Attending to the distinction highlights a symmetrical ethical dilemma: researchers studying disadvantage are often motivated to further the interests of the wider group to which their participants belong, yet the study itself risks eliciting or exacerbating negative experiences or identities amongst participants themselves. Conversely, the process of studying advantage frequently bolsters the positive identities or experiences of individual study participants, even as the research findings challenge or subvert the interests of their group.