Purpose: Nascent geographic atrophy (nGA) describes features on OCT imaging previously observed to precede the development of atrophy. This study sought to prospectively evaluate the predictive ability of nGA for the conventional clinical endpoint of geographic atrophy (GA) as defined on color fundus photography (CFP). Design: Prospective, longitudinal, observational study. Participants: A total of 284 eyes from 142 participants with bilateral large drusen and without nGA nor late age-related macular degeneration (AMD) at baseline were included. Methods: OCT volume scans and CFP images were obtained from all participants at baseline and then at 6-month intervals for up to 36 months. OCT and CFP images were graded independently for the presence of nGA and GA, respectively. Eyes that developed neovascular AMD were censored at the day of its detection. Main Outcome Measures: Time to development of GA. Results: A total 12 eyes from 10 participants progressed to GA over 36 months of follow-up, and nGA was detected in 10 of these eyes (83%) at a preceding visit (median, 13 months prior; interquartile range, 6–25 months). A total of 40 eyes from 28 participants developed nGA or GA over 36 months of follow-up, and the probability of progression to nGA and GA after 36 months was 20% (95% confidence interval [CI], 14%–28%) and 9% (95% CI, 6%–13%), respectively. After the detection of nGA, the probability of progression to GA was 38% (95% CI, 15%–55%) after 24 months. The development of nGA was associated with a markedly increased risk of progression to GA compared with when it did not develop (adjusted hazard ratio, 78.1; 95% CI, 13.6–448.0; P < 0.001), and the development of nGA explained 91% of the variance in the time to GA development. Conclusions: This study prospectively demonstrated that nGA was a strong predictor for the development of GA, providing supportive evidence of the potential value of nGA as a surrogate endpoint in future intervention trials for the early stages of AMD to improve their feasibility substantially.