People with learning disabilities do not always have chance to make decisions in their everyday lives. However, in England the Mental Capacity Act (MCA) provides a legislative framework for supporting people to make decisions. This study used Conversation Analysis of video recorded interactions between people with learning disabilities and their supporters to examine everyday decision-making. The thesis showed that assumptions of capacity were foregrounded in talk used by staff, support for people with learning disabilities to make decisions was not always appropriate and when decisions were perceived by staff to be ‘unwise’, they used subtle interactional strategies to challenge these decisions. In sum, the thesis contributes to our understanding of how decisions are made with, and for people with learning disabilities through the lens of the MCA.