Big-box retail stores arriving from foreign countries have transformed the way Mexican households shop for goods, sparking a “supermarket revolution”. Traditionally, consumers in developing countries have shopped at street markets and small, independent stores. However, consumers have switched to shopping at foreign retailers, who offer a larger variety of products at cheaper prices. Despite concerns that foreign retailers might adversely affect local employment and household incomes, our evidence shows that allowing them to operate their businesses in Mexico has generated substantial welfare gains for households across the income spectrum by lowering the cost of living, while having limited impacts on total employment, incomes, and local businesses closing.