Students with a zero expected family contribution (EFC) are those with the greatest financial need and least ability to pay for college and now make up more than one in three American undergraduate students. Yet little is known about the year-to-year financial aid volatility of these students, or whether it varies by how the zero EFC was determined. I use nationally-representative data to examine trends in zero EFC receipt over time and then use student-level data from nine colleges and universities to examine zero EFC stability over multiple years by zero EFC status. The results indicate overall stability in zero EFC receipt across multiple years, as about eight in ten students with a zero EFC keeping that status one year later. However, this masks a great deal of heterogeneity among zero EFC recipients by dependency and FAFSA filing statuses. These differences have significant policy implications for allocating scarce financial aid dollars.