As the price of a public college education has risen at well above the rate of inflation for decades, college affordability has become a key concern in public policy discussions. At the same time, recent high school graduates from lower-income and middle-income families are nearly 20 percentage points less likely to enroll in college the following year than students from high-income families. A number of states and communities have responded to these concerns by starting college promise programs, which typically promise qualified middle or high school students that they will cover part or all of tuition prices when a student enters college. A key goal of these programs is to encourage financially-needy students to think that college is possible and prepare academically for postsecondary education while they are in high school. The wave of college promise programs can be in part linked to the visibility and success of two programs in the Midwest: the Indiana 21st Century Scholars program (which began in 1990) and the Kalamazoo Promise (which began in 2005). Seven states have implemented tuition-free college programs for some or all students since 2014, highlighted by the Tennessee Promise program that covered tuition at public two-year colleges and New York's recently-enacted Excelsior Scholarship program that covers tuition for eligible students at two-year and four-year public colleges. Today, there are nearly 200 active local and state college promise or free college programs across 41 states. These programs vary considerably in their eligibility criteria, institutions covered, and financial generosity. In this brief, the body of research is detailed on the effects of three well-known college promise programs in the Midwest (Indiana's 21st Century Scholars Program, Missouri's A+ Program, and Kalamazoo Promise) before discussing some of the key questions that policymakers and funders must consider when designing college promise or tuition-free college programs.