For human-centered designers, there is nothing more valuable than discovering what matters to people-what triggers frustration and what provides ease, what brings grief and what sparks joy. That's why IDEO studies subtle and often unspoken details of daily life: habits, circumstances, thoughts, feelings, and reactions. We rely upon access to people's unguarded selves. Their trust is precious, and comes with responsibility. How do we seek and share insights about people's lives in an ethical way? Three timeless principles guide all our work: respect, honesty, and responsibility. While the concepts are well known, they're abstractions that resist concrete definition, and applying them to the ambiguities, complexities, and messy scenarios of real life is no simple task. The Little Book of Design Research Ethics provides a practical guideline, along with tools and examples from our work in the field. It integrates more than a quarter-century of IDEO experience with advice and recommendations from ethicists as well as codes of conduct in related professions, from journalism to market research. Though it was originally created for IDEO designers, the book offers applicable guidance to a wide range of situations in which it's crucial to build relationships of trust. It's the first of its kind, and we hope it will facilitate ongoing conversation and reflection about what it means to work with empathy and cultural sensitivity and ensure that interactions are safe, fair, enjoyable, and mutually beneficial.