Background: Triple negative breast cancer (TNBC) is a particularly aggressive subtype of breast cancer that is more likely to become metastatic, accounting for a proportionally higher percentage of breast cancer-related deaths. We previously assessed features associated with rapid relapse TNBC (rrTNBC) and found that higher stage at diagnosis, younger age at diagnosis, lower income, and insurance type were significantly associated with rrTNBC. The goal of the present study was to identify clinicopathologic and sociodemographic features associated with late relapse TNBC (lrTNBC). Method: We included patients diagnosed with stage I-III TNBC who received chemotherapy at one of 10 academic cancer centers between 1996 and 2012. lrTNBC was defined as distant metastatic relapse or mortality >5 years after diagnosis. Bivariable logistic regression was used to determine associations between the relevant covariates and lrTNBC. Multivariable logistic regression with backwards selection was then used to construct a final multivariable model with a p<0.10 criterion. The final multivariable model was applied to training (70%) and independent validation (30%) cohorts. Results: Of the 5,256 TNBC patients from the 10 NCCN institutions, 2,210 were included in the present analyses. Of this sample, 750 patients had lrTNBC. Bivariable analyses of the training cohort (n=1,547) identified a significant (p<0.10) association between lrTNBC and body mass index (BMI), race, income, education, insurance type, age at diagnosis, and stage at diagnosis. In the final multivariable model, lrTNBC was significantly associated with higher stage at diagnosis (adjusted Odds Ratio [aOR] for stage III vs I, 10.9; 95% Confidence Interval [CI], 7.5-15.9; p<0.0001) and BMI (aOR for obese vs normal weight, 1.4; 95% CI, 1.0-1.8; p=0.03). Final model performance was consistent between the training and validation cohorts. In sensitivity analyses stratified by stage, obese and overweight BMI was associated with lrTNBC in stage III patients, whereas only obese BMI was associated with lrTNBC in stage I and II patients. Conclusions: Late relapse in TNBC is associated with stage at diagnosis, age at diagnosis, and BMI. Taken in conjunction with our previous findings in rrTNBC, these findings may indicate that while rrTNBC is associated with socioeconomic factors, as well as biological factors, lrTNBC may be primarily influenced by biological factors.