Abstract: This law school casebook was developed by a team of professors at Harvard Law School to introduce students with little or no quantitative background to the basic analytical techniques that attorneys need to master to represent their clients effectively. This casebook presents clear explanations of decision analysis, games and information, contracting, accounting, finance, microeconomics, economic analysis of the law, fundamentals of statistics, and multiple regression analysis. References and examples have been thoroughly updated for this 3rd edition, and exposition of a number of key topics has been reworked to reflect insights gained from teaching these topics using the 1st edition to many hundreds of Harvard Law students over the past decade.