<h3>Purpose/Objective(s)</h3> While comprehensive local treatment of non-small cell lung cancer (NSCLC) oligometastatic disease (OMD) has thus far yielded promising results, challenges remain in selecting patients with a more localized oligometastatic phenotype, as opposed to those with a large subclinical systemic disease burden. We sought to identify clinical variables that predict for early polymetastatic progression after definitive local treatment to all sites of disease for synchronous oligometastatic NSCLC. <h3>Materials/Methods</h3> From 2010-2019, 2884 patients with metastatic NSCLC were treated at a single cancer center. Patients who presented with synchronous OMD, defined as 1-5 distant metastases at diagnosis of NSCLC, and who had definitive local treatment of the primary and each metastatic lesion were retrospectively identified and included for analysis. The Kaplan-Meier method was used to calculate endpoints of freedom from polymetastasis (FFPM), defined as disease recurrence with >5 new/growing lesions, as well as freedom from new metastasis (FFNM), progression-free survival (PFS), and overall survival (OS). Multivariate Cox analyses were performed on variables with significant association on univariate analyses. Patients with and without early polymetastatic progression (within 1 year of completing local treatment) were compared using Fisher's exact test and Welch's t-test. <h3>Results</h3> A cohort of 84 NSCLC patients with synchronous OMD and definitive treatment to every site of disease was identified. Median follow up was 25.4 months. 2-year FFPM, FFNM, PFS, and OS were 55.0%, 27.8%, 20.9% and 55.1%, respectively. On multivariate analysis, N2 stage (vs. N0, HR 5.10, 95%CI 2.30 – 11.32, p < 0.001), number of metastases (HR 1.61, 95%CI 1.08 – 2.38, p = 0.018), and bone metastasis (HR 6.84, 95%CI 2.41 - 19.47, p < 0.001) were associated with FFPM, while no variable maintained a significant association with FFNM. N2 stage (HR 1.91, 95%CI 1.06-3.44, p = 0.031) and brain metastasis (HR 1.98, 95%CI 1.07-3.67, p=0.029) were associated with PFS. N2 stage (HR 2.79, 95%CI 1.47-5.32, p = 0.002) and age (HR 1.06, 95%CI 1.03 – 1.09, p < 0.001) were associated with OS. When comparing the 20 patients with polymetastasis within 1 year and 55 with FFPM > 1 year (excluding patients with <1 year follow up), patients with early polymetastasis were more likely to have N2 disease (45% vs. 10.9%, p = 0.009) and bone metastasis (30% vs. 3.6%, p = 0.004). <h3>Conclusion</h3> For NSCLC patients undergoing comprehensive local treatment for synchronous OMD, bone metastasis, N stage, and number of metastases are associated with early polymetastatic progression, likely reflecting the disparate biologies among patients with synchronous OMD as well as the difficulty of identifying small bone metastases with typical imaging studies. Strategies to intensify upfront imaging and systemic treatment may benefit this subset of patients.