Abstract Purpose: To delineate recurrent oncogenic driver alterations and dysregulated pathways in esophageal adenocarcinoma and to assess their prognostic value. Experimental Design: We analyzed a large cohort of patients with lower esophageal and junctional adenocarcinoma, prospectively sequenced by MSK-IMPACT with high-quality clinical annotation. Patients were subdivided according to treatment intent, curative versus palliative, which closely mirrored clinical staging. Genomic features, alterations, and pathways were examined for association with overall survival using Cox proportional hazard models, adjusted for relevant clinicopathologic factors knowable at the time of diagnosis. Results: Analysis of 487 patients revealed 16 oncogenic driver alterations, mostly amplifications, present in ≥5% of patients. Patients in the palliative-intent cohort, compared with those in the curative-intent cohort, were more likely to have metastatic disease, ERBB2 amplifications, Cell-cycle and RTK–RAS pathway alterations, as well as a higher fraction of genome altered and rate of whole-genome doubling. In multivariable analyses, CDKN2A alterations, SMAD4 alterations, KRAS amplifications, Cell-cycle and TGFβ pathways, and overall number of oncogenic drivers were independently associated with worse overall survival. ERBB2 amplification was associated with improved survival, presumably due to trastuzumab therapy. Conclusions: Our study suggests that higher levels of genomic instability are associated with more advanced disease in esophageal adenocarcinoma. Furthermore, CDKN2A, KRAS, and SMAD4 represent prognostic biomarkers, given their strong association with poor survival.