Experiments with lotteries during European democratization can inform proposed democratic innovations today. Recently, lotteries have put citizens together to find solutions to today’s contentious, polarizing issues. The ideal, but unfeasible experiment would randomly vary group characteristics, assign real political power, and observe effects over time. Instead, this project draws lessons from past experiments during democratisation in parliaments in Europe - whereby legislators were randomly assigned to committees - and experiments with such lotteries in online citizens’ assemblies today. These natural experiments with lotteries have never before been digitised and investigated using modern statistical methods, to understand the role of their institutional design and context in opening access to politics. Novel, comparative datasets of legislators, parliamentary activity and offices from different European countries is compiled. Next, the consequences of these lotteries will be analysed within each country, and in a present-day experiment that allows controlled conditions. By opening access to minorities and contributing to strong, deliberative party and committee systems, lotteries reduced polarization and stabilised political conflict over time. From such real politics and lotteries, when inequality and polarization was high, we can better understand the likely long-term effects of combining lotteries and representative democracy today.