School systems aspire to provide equal opportunity for all, irrespective of socio-economic status (SES). Much of the criticism of recent school reforms that introduce accountability, autonomy, and choice emphasizes their potentially negative consequences for equity. This report provides new evidence on how national features of accountability, autonomy, and choice are related to the equality of opportunity across countries. We estimate whether student achievement depends more or less on SES in school systems employing these institutional features. The rigorous micro-econometric analyses are based on the PISA 2003 data for more than 180,000 students from 27 OECD countries. The main empirical result is that rather than harming disadvantaged students, accountability, autonomy, and choice appear to be tides that lift all boats. The additional choice created by public funding for private schools in particular is associated with a strong reduction in the dependence of student achievement on SES. External exit exams have a strong positive effect for all students that is slightly smaller for low-SES students. The positive effect of regularly using subjective teacher ratings to assess students is substantially larger for low-SES students. The effect of many other accountability devices does not differ significantly by student SES. School autonomy in determining course content is associated with higher equality of opportunity, while equality of opportunity is lower in countries where more schools have autonomy in hiring teachers. Autonomy in formulating the budget and in establishing starting salaries is not associated with the equity of student outcomes. Inequality of opportunity is substantially higher in school systems that track students at early ages. (Contains 19 footnotes, 6 figures and 9 tables.)