Children's museums have been increasing rapidly since their beginnings in the nineteenth century, and especially so in the past 30 years. This article is based on my observations of 30 children's museums in Europe, North America, South America and the Middle East and the article briefly discusses the history and development of children's museums, their definitions, missions/goals and models of children's museums. Then, trends related to types of exhibits, programming and outreach activities are presented. Finally, some frequent challenges and issues around the establishment and continuation of children's museums such as funding, sponsorship, attendance, exhibit design and technology are discussed. A summary of research on children's museums is included.