Children have a basic, evolved need for attachment to other individuals who can provide security as well as supplying physical needs such as food, warmth, clothing and shelter. Children can and do form multiple attachments with those people around them who provide ongoing care. Secure attachments are based on sensitive, emotionally responsive and attuned carer behaviours, and are associated with positive developmental outcomes. Finally, based on their experiences with those who care for them, children construct mental representations of what it is to be in a relationship with another. The ethics of research with children need careful consideration, and the British Psychological Society’s Code of Human Research Ethics gives special attention to the issues involved.