he United Nations Convention on the Rights of Persons with Disabilities adopted in 2006 holds States responsible to “…collect appropriate information, including statistical and research data, to enable them to formulate and implement policies…” This recognition has led to an increasing number of countries gathering data on disability at the population level; however, there are currently no gold standards for its measurement and different data collection tools have been used throughout the years to fulfil data needs. Understanding how these differences have influenced the measurement of disability globally is crucial to developing reliable and comparable measures. The purpose of this paper is to describe the varying scope and content of data collection instruments on child disability and to provide a historical snapshot of the rates of reported disability among children. A total of 716 data sources were identified, corresponding to 198 countries covering more than 95% of the world's children. The findings reveal a lack of consistent definitions and measures of disability, which contribute to major challenges in producing reliable and comparable statistics.