Would replacing the conventional work week with a four-day option benefit economic performance and well-being? In the framework of economics, the question is whether work week reform can make some individuals better off without making other individuals worse off in ways that do not hamper other goals such as efficiency, economic growth, and equity. Social and individual welfare outcomes would depend on whether reforming the work week involves shortening the length of the work day versus rearranging the timing of work. The “public good” case for a policy that induces shorter hours of work per employee is a logical extension from evidence of the adverse effects stemming from excessively long hours of work on workers’ stress, work/life balance...