This paper looks at the existing tools and approaches most commonly used in developed and developing countries to review the stock of regulations. The tools reviewed can generate benefits in the short term, but they are most effective as part of a longer-term sustained initiative. This paper has a particular focus on the challenges that arise from their use in emerging and developing countries. The objectives of this paper include: 1) explaining the rationale for the use of these tools and approaches; 2) discussing each one of them in a succinct way; 3) considering the extent to which these tools can support more systemic regulatory reforms in the medium and long terms; and 4) considering the particular challenges and opportunities regarding their use in developing and emerging economies. Section one is a brief description of the rationale and context for applying tools and approaches to review the stock of regulation. It includes a reference to benefits and preconditions to make use of these tools. It also presents a categorization of the most commonly used tools and a comparative table on the way these tools can be applied. Section two presents a description of each of the different tools and approaches available, and discusses the way they are used and their main components. It includes references to international experiences in which these tools have been integrated into the regulatory reform process. Section three presents preliminary commentary about some of the potential advantages, disadvantages, and impacts of using these tools and approaches in developing countries. Some particular cases are presented to illustrate these trends. The section also includes a short description of the sequence observed in the use of some of these tools. Moreover, this section illustrates how these tools can (or cannot) generate gains in the short term and also provide a basis for further and broader regulatory reform programs.