The Washington Group on Disability Statistics is a voluntary working group made up of representatives of over 100 National Statistical Offices and international, non-governmental and disability organizations that was organized under the aegis of the United Nations Statistical Division. The purpose of the Washington Group is to deal with the challenge of disability definition and measurement in a way that is culturally neutral and reasonably standardized among the UN member states. The work, which began in 2001, took on added importance with the passage and ratification of the UN Convention on the Rights of Persons with Disabilities since the Convention includes a provision for monitoring whether those with and without disabilities have equal opportunities to participate in society and this will require the identification of persons with disabilities in each nation. The International Classification of Functioning, Disability and Health (ICF) developed by the World Health Organization provided a framework for conceptualizing disability. Operationalizing an ICF-based approach to disability has required the development of new measurement tools for use in both censuses and surveys. To date, a short set of six disability-related questions suitable for use in national censuses has been developed and adopted by the Washington Group and incorporated by the United Nations in their Principles and Recommendations for Population and Housing Censuses. A series of extended sets of questions is currently under development and some of the sets have been tested in several countries. The assistance of many National and International organizations has allowed for cognitive and field testing of the disability questionnaires in multiple languages and locations. This paper will describe the work of the Washington Group and explicate the applicability of its approach and the questions developed for monitoring the UN Convention on the Rights of Persons with Disabilities.