Abstract Objectives To develop a modified Nutrition Rich Food Index (PS-NRF) to assess the nutrient density (ND) of protein snack foods, based on the nutritional profile of most commonly consumed protein-rich food items, which can be used to develop nutrient-dense protein snacks. Methods Good source protein food items, defined as ready-to-eat food items with ≥10% of the US protein daily value (DV), were selected from the 450 most frequently consumed food items by the NHANES 2013–14 participants aged ≥2y. Principal component analysis (PCA) was conducted on the 7 encouraged micronutrients in the original NRF 9.3 calculation (vitamins A, C, D, calcium, iron, potassium and magnesium) to determine which would be appropriate for the PS-NRF. PS-NRF was calculated by subtracting the sum of percentages of maximum recommended values for discouraged nutrients (saturated fat, total sugar and sodium) from the sum of percentages of DVs for encouraged nutrients (protein, fiber and select micronutrients from this study), capped at 100% per DV. In order to use healthy food options as the basis, only positive PS-NRF/100 kcal values were used to calculate the mean, median, and inter-quartile range (IQR) of the good protein source food items and target those items with accompanying nutrient(s) to encourage. Results One hundred and sixty-nine good source protein food items were identified (17.16% Milk and Milk Products, 29% Meat, Poultry, Fish and mixtures, 23.67% Eggs, 21.3% Legumes, nuts and seeds, and 8.88% grain products). According to the PCA, vitamin A (r = −0.61), vitamin D (r = −0.49), and calcium (r = −0.53) had relatively stronger strengths of correlation compared to other micronutrients and therefore included in the PS-NRF. Based on this approach, 127 (75.15%) good source protein food items were found to have positive PS-NRF. The mean ± SD and median (IQR) of the PS-NRF/100 kcal index were: 12.23 ± 10.95 and 10.22 (4.72 to 16.35). Conclusions This study demonstrated that in good source protein food items, vitamins A, D and calcium were found to be accompanying nutrients that were influential contributors to the DVs and were included as encouraged micronutrients in the PS-NRF. The mean PS-NRF among all good source protein food items with positive PS-NRF was 12.23/100 kcal, which could be used as a reference to differentiate healthy protein snack foods with good nutrient density. Funding Sources None.