Objective: To use multimodal assessment (fluorescein angiography [FA], color fundus photography [CFP], and spectral-domain-OCT [SD-OCT]) to reevaluate macular atrophy (MA) and macular neovascularization (MNV) type in the HARBOR trial according to the consensus on neovascular age-related macular degeneration (nAMD) Nomenclature criteria; and to determine if there are any associations between baseline demographic factors, ocular characteristics, and treatment for nAMD and the development of MA by month 24. Design: Post hoc analysis of the phase III, randomized, multicenter, double-masked, controlled HARBOR trial (NCT00891735). Subjects: Nine-hundred and twenty-two study eyes and 919 fellow eyes from the HARBOR trial.Methods: This post hoc analysis included patients with multimodal assessments on FA, CFP, and SD-OCT at baseline. A risk analysis for the development of MA was performed by multimodal assessment and SD-OCT on study eyes without MA at baseline that had completed SD-OCT assessments for MA at month 24.Main Outcome Measures: Development of MA in study eyes at month 24 and a risk analysis for developing MA at month 24 in study eyes that had no MA at baseline, as assessed by multimodal assessment.Results: Of 1097 patients in the HARBOR trial with nAMD and active subfoveal MNV, a total of 922 study eyes and 919 fellow eyes were included in the multimodal analysis of MNV. Macular atrophy assessment was performed on SD-OCT. Of these, 593 had no baseline MA and were included in the risk analysis for developing MA. In eyes with no detectable MA at baseline, a larger proportion of eyes with any MNV type 3 (including mixed type) at baseline developed new MA at month 24 (49.2%) than eyes with MNV type 1 (26.5%), type 2 (29.1%), or mixed type 1 and 2 (34.6%). Macular neovascularization type 3 and fellow eye MA were identified as risk factors for new MA development at month 24. Conclusions: Macular neovascularization type 3 was a strong risk factor for new MA development at month 24, with fellow eye MA also being identified as a predictor. No other variables, including ranibizumab treatment, were identified as risk factors for new MA development.Financial Disclosure(s): Proprietary or commercial disclosure may be found after the references. Ophthalmology Retina 2023;7:300-306 (c) 2023 Published by Elsevier Inc. on behalf of the American Academy of Ophthalmology