We collect data on management practices in over 1,800 high schools in eight countries. We show that higher management quality is strongly associated with better educational outcomes. The UK, Sweden, Canada and the US obtain the highest management scores, followed by Germany, with a gap before Italy, Brazil and India. We also show that autonomous government schools (government funded but with substantial independence like UK academies and US charters) have higher management scores than regular government or private schools. Almost half of the difference between the management scores of autonomous and regular government schools is accounted for principal leadership and governance. There are major disparities in the quality of education within and between countries (OECD, 2012). School managerial practices may be an important reason for such differences. Unfortunately, understanding the role of management in schools within and across countries has been held back by a lack of robust and comparable instruments to systematically measure management practices and, thus, a lack of good data. The key purpose of this article is to develop an international management index for schools and present descriptive evidence on management quality and education outcomes across schools of different types within and across countries. We used double-blind telephone interviews with school principals to collect information on management practices for over 1,800 schools across eight countries. To construct our management index, we average across 20 basic management practice measures in four areas of management: operations, monitoring, target setting and people. Each question is evaluated against a scoring grid that ranges from one (‘worst practice’) to five (‘best practice’). Our management index for each school represents the average of these scores. We also constructed measures of school-level pupil outcomes for these schools (when data were available) from examination results across regions and countries, creating a matched management-pupil outcome international data set at the school level. These data allow us to document some stylised facts. First, we show that the adoption of basic managerial practices varies significantly across and within countries. The UK, Sweden, Canada and the US obtain the highest average scores, followed by Germany, Italy and Brazil, while India has the lowest scores. About half of the variance in school management is at the country-level. This share is larger in education than we have