Placing students on academic probation is a pervasive practice at colleges and universities, but the lasting impact—and arguably even the purpose—of academic probation is unclear. The present study explored the influence of academic probation on four-year graduation using regression discontinuity analyses with a dataset of 9,777 undergraduates. The results frequently identified large or very large negative effects of probationary placement on four-year graduation, and these were greatest for probationary criteria based on either semester GPA or an overall GPA criterion in which students had accrued fewer than 30 total college credits. The findings were robust across analytic approaches and were observed regardless of students’ race, sex, first-generation status, high school GPA, and standardized test scores; the effects were sometimes larger among students who had higher high school GPAs and female students. Supplemental analyses suggest that the graduation effects based on cutoffs for college semester GPA and early overall GPA were predominantly or entirely driven by attrition that occurred soon after the probationary placement, whereas graduation effects based on the overall GPA cutoff with at least 30 college credits appeared to be driven mostly by delaying time to degree. These findings have critical implications for institutional policy and practice.