The right to participate in choosing or changing a constitution is becoming established in law and theory. The means of realising that right in the formation of Bills of Rights, and the consequences for democratic legitimacy, are matters of debate and experimentation. This chapter explores the processes used to develop Bills of Rights (or proposed Bills) in the United Kingdom, Canada, Australia, and New Zealand, and analyses key aspects of the design of those processes. It examines the context for creating a new UK Bill of Rights, including the work of the Commission on a Bill of Rights established in 2011. It reflects on the challenges facing the Commission in the light of experience overseas. It concludes that, on present evidence, the Commission is highly unlikely to achieve an outcome which might enjoy democratic legitimacy, in the sense of having been subject to inclusive and informed public deliberation.