The Sphere Project (consisting of both the Humanitarian Charter and Minimum Standards for Disaster Response) has made prominent contributions to the debates, thinking and work on the quality of assistance and accountability of aid agencies. However, since its inception in 1997, several agencies expressed concerns regarding Sphere's approach, many of which were confirmed by the Sphere evaluation (2002/3). The present article restates these concerns, and addresses more fundamental issues regarding Sphere's cornerstone. It questions the validity of Sphere's rights-based approach, which consists of a tenuous link between the rights of affected populations and standards for technical interventions. Sphere is founded on "the right to assistance", although this right does not exist in international law. Its elaboration would entail solving several complex legal and political issues, which Sphere fails to address. This article also questions the validity and usefulness of universal standards for technical performance in helping relief agencies provide adapted assistance to disaster-affected populations, in line with their mandates and principles. It suggests that Sphere's approach and content largely reflect the concerns, priorities and values of technical professionals in Northern agencies, leaving limited space to genuine "participation" by affected populations and partners from the South.