The Gale-Shapley stable marriage theorem is a fascinating piece of twentieth-century mathematics that has many practical applications--from labor markets to school admissions--yet is accessible to secondary school mathematics students. David Gale and Lloyd Shapley were both mathematicians and economists who published their work on the Stable Marriage problem in 1962. Shapley received the 2012 Nobel Prize in Economics for his work on stable allocations. Because the Nobel Prize is not awarded posthumously, Gale, who died in 2008, did not share in the prize. The proof of the theorem is constructive: There exists an algorithm that will always solve the problem. Moreover, a class activity allows students to carry out the steps of the algorithm as a group and see how it works. The activity presented in this article helps fulfill the fourth Standard for Mathematical Practice (Model with Mathematics): "Mathematically proficient students can apply the mathematics they know to solve problems arising in everyday life, society, and the workplace". A bibliography is included.