The relationship between education and inequality has been an important subject for historians of education, as well as sociologists, economists, political scientists of education and policy makers. Although for the past two decades educational policy internationally has emphasized reducing achievement gaps through both state and private educational systems, attempts to increase access to education and decrease educational inequalities has its origins in the 19th and 20th centuries. Neo-institutional historians and sociologists of education have analyzed historically the rise of mass public educational systems beginning in the 19th century as part of a worldwide expansion of civil society and democratic principles. Neo-Marxist and revisionist historians have analyzed the ways in which educational reforms aimed at reducing inequalities are in contradiction to the social reproduction function of education in capitalist societies. Comparative and international historians of education have provided important accounts of the similarities and differences of mass public systems as they developed in an increasingly globalized world. Finally, historians and sociologists of education have examined the development of educational policies aimed at reducing educational and social inequalities, including marketization and privatization and state policies including national curriculum and testing legislation in the U.K. and the No Child Left Behind Law in the United States.