Piketty's work did what decades of rising disparities couldn't do: it reminded macroeconomists that inequality matters. More starkly, it laid bare just how ill-equipped our existing frameworks are for understanding, predicting, and changing inequality. This extraordinary collection shows that our most nimble social scientists are responding to the challenge, collecting ideas about capital, technology, power, gender, race, and privilege that might help inform a broader understanding.–Justin Wolfers, University of Michigan