This white paper considers the affordability of four-year public institutions for an average Pell Grant recipient who receives the average amount of grant aid, takes out the average amount of federal loans, and collects reasonable work wages to contribute to an education. An astounding 75 percent of residential four-year institutions--including 90 percent of flagships--failed National College Access Network's (NCAN's) affordability test. The average Pell Grant recipient in NCAN's model would be able to afford just 139 of 551 residential four-year public institutions across the United States. This white paper specifically explores public colleges and universities for in-state students because access to higher education for the residents of their states is the mission of these institutions. In addition to laying out the formula for how affordability is measured, the white paper also explores how affordability differs for students who are unable to live on campus, unable to contribute summer earnings toward their education, or both. [Allie Ciaramella contributed to the writing of this report.]