Over the last few years there has been considerable discussion in scientific, policy and public fora on the effectiveness of peer review systems, including those employed by journals, research institutes or agencies. These discussions have focused on how to select qualified reviewers, develop appropriate instructions for reviewers, select a suitable format for the review, and more importantly, how to ensure that peer reviews are scientifically rigorous and appropriate for the end use of the information. In August 2003, OMB released a draft bulletin that updates it's Information Quality Guidelines (IQG) to include additional guidance on how federal agencies should peer review scientific, technical, and economic information that will serve as the basis for a 'significant regulatory decision'. This draft guidance reinforces these earlier discussions and raises many new questions. It also identifies a new topic for debate, briefly "Should peer review for 'significant' information used to support a regulatory decision be different from other agency peer reviews, and if so, how?" This presentation will highlight these new questions and challenges posed by OMB's draft guidelines in an effort to assist agencies and other groups as they prepare to respond to OMB and modify their existing practices.